diff --git a/pipenv/cli.py b/pipenv/cli.py
index 56e62969..449cd3c8 100644
--- a/pipenv/cli.py
+++ b/pipenv/cli.py
@@ -503,9 +503,6 @@ def lock(
 
     # Ensure that virtualenv is available.
     core.ensure_project(three=three, python=python)
-    # Load the --pre settings from the Pipfile.
-    if not pre:
-        pre = core.project.settings.get('pre')
     if requirements:
         core.do_init(dev=dev, requirements=requirements)
     core.do_lock(
@@ -739,9 +736,6 @@ def update(
                 crayons.white('.', bold=True),
             )
         )
-        # Load the --pre settings from the Pipfile.
-        if not pre:
-            pre = core.project.settings.get('pre')
         core.do_lock(
             verbose=verbose, clear=clear, pre=pre, keep_outdated=keep_outdated
         )
diff --git a/pipenv/core.py b/pipenv/core.py
index a5f016b0..91f07f2a 100644
--- a/pipenv/core.py
+++ b/pipenv/core.py
@@ -1011,6 +1011,8 @@ def do_lock(
     from notpip._vendor.distlib.markers import Evaluator
     allowed_marker_keys = ['markers'] + [k for k in Evaluator.allowed_values.keys()]
     cached_lockfile = {}
+    if not pre:
+        pre = project.settings.get('allow_prereleases')
     if keep_outdated:
         if not project.lockfile_exists:
             click.echo(
@@ -1634,8 +1636,11 @@ def warn_in_virtualenv():
             click.echo(
                 '{0}: Pipenv found itself running within a virtual environment, '
                 'so it will automatically use that environment, instead of '
-                'creating its own for any project.'.format(
-                    crayons.green('Courtesy Notice')
+                'creating its own for any project. You can set '
+                '{1} to force pipenv to ignore that environment and create '
+                'its own instead.'.format(
+                    crayons.green('Courtesy Notice'),
+                    crayons.normal('PIPENV_IGNORE_VIRTUALENVS=1', bold=True),
                 ),
                 err=True,
             )
@@ -1643,7 +1648,6 @@ def warn_in_virtualenv():
 
 def ensure_lockfile(keep_outdated=False):
     """Ensures that the lockfile is up–to–date."""
-    pre = project.settings.get('allow_prereleases')
     if not keep_outdated:
         keep_outdated = project.settings.get('keep_outdated')
     # Write out the lockfile if it doesn't exist, but not if the Pipfile is being ignored
@@ -1660,9 +1664,9 @@ def ensure_lockfile(keep_outdated=False):
                 ),
                 err=True,
             )
-            do_lock(pre=pre, keep_outdated=keep_outdated)
+            do_lock(keep_outdated=keep_outdated)
     else:
-        do_lock(pre=pre, keep_outdated=keep_outdated)
+        do_lock(keep_outdated=keep_outdated)
 
 
 def do_py(system=False):
@@ -2017,8 +2021,6 @@ def do_uninstall(
         system = True
     # Ensure that virtualenv is available.
     ensure_project(three=three, python=python)
-    # Load the --pre settings from the Pipfile.
-    pre = project.settings.get('allow_prereleases')
     package_names = (package_name,) + more_packages
     pipfile_remove = True
     # Un-install all dependencies, if --all was provided.
@@ -2085,7 +2087,7 @@ def do_uninstall(
             project.remove_package_from_pipfile(package_name, dev=True)
             project.remove_package_from_pipfile(package_name, dev=False)
     if lock:
-        do_lock(system=system, pre=pre, keep_outdated=keep_outdated)
+        do_lock(system=system, keep_outdated=keep_outdated)
 
 
 def do_shell(three=None, python=False, fancy=False, shell_args=None):
@@ -2183,7 +2185,7 @@ def inline_activate_virtualenv():
         activate_this = which('activate_this.py')
         with open(activate_this) as f:
             code = compile(f.read(), activate_this, 'exec')
-            exec (code, dict(__file__=activate_this))
+            exec(code, dict(__file__=activate_this))
     # Catch all errors, just in case.
     except Exception:
         click.echo(
diff --git a/pipenv/patched/contoml/file/file.py b/pipenv/patched/contoml/file/file.py
index 16017b99..99ce1483 100755
--- a/pipenv/patched/contoml/file/file.py
+++ b/pipenv/patched/contoml/file/file.py
@@ -231,7 +231,7 @@ class TOMLFile:
         if has_anonymous_entry():
             return items
         else:
-            return items + [('', self[''])]
+            return list(items) + [('', self[''])]
 
     @property
     def primitive(self):
diff --git a/pipenv/patched/pipfile/api.py b/pipenv/patched/pipfile/api.py
index 08aa49c3..18a1ea23 100644
--- a/pipenv/patched/pipfile/api.py
+++ b/pipenv/patched/pipfile/api.py
@@ -9,6 +9,13 @@ import sys
 import os
 
 
+DEFAULT_SOURCE = {
+    u'url': u'https://pypi.python.org/simple',
+    u'verify_ssl': True,
+    u'name': u'pypi',
+}
+
+
 def format_full_version(info):
     version = '{0.major}.{0.minor}.{0.micro}'.format(info)
     kind = info.releaselevel
@@ -89,7 +96,7 @@ class PipfileParser(object):
 
         # Load the default configuration.
         default_config = {
-            u'source': [{u'url': u'https://pypi.python.org/simple', u'verify_ssl': True, 'name': "pypi"}],
+            u'source': [DEFAULT_SOURCE],
             u'packages': {},
             u'requires': {},
             u'dev-packages': {}
diff --git a/pipenv/project.py b/pipenv/project.py
index 4b8d1bb7..9da86876 100644
--- a/pipenv/project.py
+++ b/pipenv/project.py
@@ -12,6 +12,7 @@ import hashlib
 import contoml
 import delegator
 import pipfile
+import pipfile.api
 import toml
 
 from pip9 import ConfigOptionParser
@@ -51,6 +52,26 @@ if PIPENV_PIPFILE:
 _pipfile_cache = {}
 
 
+if PIPENV_TEST_INDEX:
+    DEFAULT_SOURCE = {
+        u'url': PIPENV_TEST_INDEX,
+        u'verify_ssl': True,
+        u'name': u'custom',
+    }
+else:
+    DEFAULT_SOURCE = {
+        u'url': u'https://pypi.python.org/simple',
+        u'verify_ssl': True,
+        u'name': u'pypi',
+    }
+
+pipfile.api.DEFAULT_SOURCE = DEFAULT_SOURCE
+
+
+class SourceNotFound(KeyError):
+    pass
+
+
 class Project(object):
     """docstring for Project"""
 
@@ -490,35 +511,20 @@ class Project(object):
         config_parser = ConfigOptionParser(name=self.name)
         install = dict(config_parser.get_config_section('install'))
         indexes = install.get('extra-index-url', '').lstrip('\n').split('\n')
-        if PIPENV_TEST_INDEX:
-            sources = [
-                {
-                    u'url': PIPENV_TEST_INDEX,
-                    u'verify_ssl': True,
-                    u'name': u'custom',
-                }
-            ]
-        else:
-            # Default source.
-            pypi_source = {
-                u'url': u'https://pypi.python.org/simple',
-                u'verify_ssl': True,
-                u'name': 'pypi',
-            }
-            sources = [pypi_source]
-            for i, index in enumerate(indexes):
-                if not index:
-                    continue
+        sources = [DEFAULT_SOURCE]
+        for i, index in enumerate(indexes):
+            if not index:
+                continue
 
-                source_name = 'pip_index_{}'.format(i)
-                verify_ssl = index.startswith('https')
-                sources.append(
-                    {
-                        u'url': index,
-                        u'verify_ssl': verify_ssl,
-                        u'name': source_name,
-                    }
-                )
+            source_name = 'pip_index_{}'.format(i)
+            verify_ssl = index.startswith('https')
+            sources.append(
+                {
+                    u'url': index,
+                    u'verify_ssl': verify_ssl,
+                    u'name': source_name,
+                }
+            )
         data = {
             u'source': sources,
             # Default packages.
@@ -565,15 +571,8 @@ class Project(object):
 
         if 'source' in self.parsed_pipfile:
             return self.parsed_pipfile['source']
-
         else:
-            return [
-                {
-                    u'url': u'https://pypi.python.org/simple',
-                    u'verify_ssl': True,
-                    'name': 'pypi',
-                }
-            ]
+            return [DEFAULT_SOURCE]
 
     def get_source(self, name=None, url=None):
         for source in self.sources:
@@ -584,6 +583,7 @@ class Project(object):
             elif url:
                 if source.get('url') in url:
                     return source
+        raise SourceNotFound(name or url)
 
     def destroy_lockfile(self):
         """Deletes the lockfile."""
diff --git a/pipenv/utils.py b/pipenv/utils.py
index 741826f3..7d60e440 100644
--- a/pipenv/utils.py
+++ b/pipenv/utils.py
@@ -1207,7 +1207,7 @@ class TemporaryDirectory(object):
     in it are removed.
     """
 
-    def __init__(self, suffix=None, prefix=None, dir=None):
+    def __init__(self, suffix, prefix, dir=None):
         if 'RAM_DISK' in os.environ:
             import uuid
 
diff --git a/tests/pypi/multidict/multidict-4.1.0.tar.gz b/tests/pypi/multidict/multidict-4.1.0.tar.gz
new file mode 100644
index 00000000..89adbb22
Binary files /dev/null and b/tests/pypi/multidict/multidict-4.1.0.tar.gz differ
diff --git a/tests/pypi/sqlalchemy/SQLAlchemy-1.2.0b3.tar.gz b/tests/pypi/sqlalchemy/SQLAlchemy-1.2.0b3.tar.gz
new file mode 100644
index 00000000..40eafa66
Binary files /dev/null and b/tests/pypi/sqlalchemy/SQLAlchemy-1.2.0b3.tar.gz differ
diff --git a/tests/pypi/tablib/tablib-0.11.5.tar.gz b/tests/pypi/tablib/tablib-0.11.5.tar.gz
new file mode 100644
index 00000000..460cd0a7
Binary files /dev/null and b/tests/pypi/tablib/tablib-0.11.5.tar.gz differ
diff --git a/tests/pypi/tablib/tablib-0.12.0.tar.gz b/tests/pypi/tablib/tablib-0.12.0.tar.gz
new file mode 100644
index 00000000..36ab89f2
Binary files /dev/null and b/tests/pypi/tablib/tablib-0.12.0.tar.gz differ
diff --git a/tests/pypi/vcrpy/vcrpy-1.11.0.tar.gz b/tests/pypi/vcrpy/vcrpy-1.11.0.tar.gz
new file mode 100644
index 00000000..605bce97
Binary files /dev/null and b/tests/pypi/vcrpy/vcrpy-1.11.0.tar.gz differ
diff --git a/tests/pypi/wrapt/wrapt-1.10.11.tar.gz b/tests/pypi/wrapt/wrapt-1.10.11.tar.gz
new file mode 100644
index 00000000..7f6870e2
Binary files /dev/null and b/tests/pypi/wrapt/wrapt-1.10.11.tar.gz differ
diff --git a/tests/pytest-pypi/pytest_pypi.egg-info/PKG-INFO b/tests/pytest-pypi/pytest_pypi.egg-info/PKG-INFO
index 966cd7ad..50322734 100644
--- a/tests/pytest-pypi/pytest_pypi.egg-info/PKG-INFO
+++ b/tests/pytest-pypi/pytest_pypi.egg-info/PKG-INFO
@@ -6,7 +6,6 @@ Home-page: https://github.com/kennethreitz/pytest-pypi
 Author: Kenneth Reitz
 Author-email: me@kennethreitz.org
 License: MIT
-Description-Content-Type: UNKNOWN
 Description: pytest-httpbin
         ==============
         
diff --git a/tests/test_pipenv.py b/tests/test_pipenv.py
index 42865df2..5c12a9b4 100644
--- a/tests/test_pipenv.py
+++ b/tests/test_pipenv.py
@@ -11,6 +11,7 @@ from pipenv.utils import (
 )
 from pipenv.vendor import toml
 from pipenv.vendor import delegator
+from pipenv.vendor import requests
 from pipenv.patched import pipfile
 from pipenv.project import Project
 from pipenv.vendor.six import PY2
@@ -23,15 +24,31 @@ try:
 except ImportError:
     from pipenv.vendor.pathlib2 import Path
 
-py3_only = pytest.mark.skipif(sys.version_info < (3, 0), reason="requires Python3")
-nix_only = pytest.mark.skipif(os.name != 'nt', reason="doesn't run on windows")
-
 os.environ['PIPENV_DONT_USE_PYENV'] = '1'
 os.environ['PIPENV_IGNORE_VIRTUALENVS'] = '1'
 os.environ['PIPENV_VENV_IN_PROJECT'] = '1'
 os.environ['PYPI_VENDOR_DIR'] = os.path.sep.join([os.path.dirname(__file__), 'pypi'])
 
 
+def check_internet():
+    try:
+        # Kenneth represents the Internet LGTM.
+        resp = requests.get('http://httpbin.org/ip', timeout=1.0)
+        resp.raise_for_status()
+    except Exception:
+        warnings.warn('Cannot connect to HTTPBin...', ResourceWarning)
+        warnings.warn('Will skip tests requiring Internet', ResourceWarning)
+        return False
+    return True
+
+
+WE_HAVE_INTERNET = check_internet()
+
+needs_internet = pytest.mark.skipif(not WE_HAVE_INTERNET, reason='requires internet')
+py3_only = pytest.mark.skipif(sys.version_info < (3, 0), reason="requires Python3")
+nix_only = pytest.mark.skipif(os.name != 'nt', reason="doesn't run on windows")
+
+
 @pytest.fixture(scope='module')
 def pip_src_dir(request):
     old_src_dir = os.environ.get('PIP_SRC', '')
@@ -46,13 +63,16 @@ def pip_src_dir(request):
     return request
 
 
-class PipenvInstance():
+VERBOSE_COMMANDS = ('install', 'lock', 'uninstall')
+
+
+class PipenvInstance(object):
     """An instance of a Pipenv Project..."""
     def __init__(self, pypi=None, pipfile=True, chdir=False):
         self.pypi = pypi
         self.original_umask = os.umask(0o007)
         self.original_dir = os.path.abspath(os.curdir)
-        self._path = TemporaryDirectory(suffix='project', prefix='pipenv')
+        self._path = TemporaryDirectory(suffix='-project', prefix='pipenv-')
         self.path = self._path.name
         # set file creation perms
         self.pipfile_path = None
@@ -91,7 +111,11 @@ class PipenvInstance():
         if self.pipfile_path:
             os.environ['PIPENV_PIPFILE'] = self.pipfile_path
 
-        c = delegator.run('pipenv {0}'.format(cmd), block=block)
+        with TemporaryDirectory(prefix='pipenv-', suffix='-cache') as tempdir:
+            os.environ['PIPENV_CACHE_DIR'] = tempdir.name
+            c = delegator.run('pipenv {0}'.format(cmd), block=block)
+            if 'PIPENV_CACHE_DIR' in os.environ:
+                del os.environ['PIPENV_CACHE_DIR']
 
         if 'PIPENV_PIPFILE' in os.environ:
             del os.environ['PIPENV_PIPFILE']
@@ -182,6 +206,7 @@ class TestPipenv:
             assert 'Warning: Using both --reverse and --json together is not supported.' in c.err
 
     @pytest.mark.cli
+    @needs_internet
     def test_pipenv_check(self, pypi):
         with PipenvInstance(pypi=pypi) as p:
             p.pipenv('install requests==1.0.0')
@@ -354,7 +379,8 @@ tablib = "*"
             shutil.copy(source_path, os.path.join(p.path, file_name))
             os.mkdir(os.path.join(p.path, "tablib"))
             c = p.pipenv('install {}'.format(file_name))
-            c = p.pipenv('uninstall --all --verbose')
+            assert c.return_code == 0
+            c = p.pipenv('uninstall --all')
             assert c.return_code == 0
             assert 'tablib' in c.out
             assert 'tablib' not in p.pipfile['packages']
@@ -442,7 +468,8 @@ setup(
 
     @pytest.mark.vcs
     @pytest.mark.install
-    def test_basic_vcs_install(self, pypi):
+    @needs_internet
+    def test_basic_vcs_install(self, pip_src_dir, pypi):
         with PipenvInstance(pypi=pypi) as p:
             c = p.pipenv('install git+https://github.com/requests/requests.git#egg=requests')
             assert c.return_code == 0
@@ -457,6 +484,7 @@ setup(
     @pytest.mark.e
     @pytest.mark.vcs
     @pytest.mark.install
+    @needs_internet
     def test_editable_vcs_install(self, pip_src_dir, pypi):
         with PipenvInstance(pypi=pypi) as p:
             c = p.pipenv('install -e git+https://github.com/requests/requests.git#egg=requests')
@@ -546,8 +574,9 @@ tpfd = "*"
     @pytest.mark.install
     @pytest.mark.resolver
     @pytest.mark.backup_resolver
-    def test_backup_resolver(self, pypi):
-        with PipenvInstance(pypi=pypi) as p:
+    @needs_internet
+    def test_backup_resolver(self):
+        with PipenvInstance() as p:
             with open(p.pipfile_path, 'w') as f:
                 contents = """
 [packages]
@@ -561,8 +590,6 @@ tpfd = "*"
 
     @pytest.mark.run
     @pytest.mark.markers
-    @pytest.mark.install
-    @pytest.mark.failed
     def test_package_environment_markers(self, pypi):
 
         with PipenvInstance(pypi=pypi) as p:
@@ -605,10 +632,10 @@ requests = {version = "*", os_name = "== 'splashwear'"}
 
     @pytest.mark.markers
     @pytest.mark.install
-    def test_top_level_overrides_environment_markers(self):
+    def test_top_level_overrides_environment_markers(self, pypi):
         """Top-level environment markers should take precedence.
         """
-        with PipenvInstance() as p:
+        with PipenvInstance(pypi=pypi) as p:
             with open(p.pipfile_path, 'w') as f:
                 contents = """
 [packages]
@@ -624,7 +651,7 @@ funcsigs = {version = "*", os_name = "== 'splashwear'"}
 
     @pytest.mark.markers
     @pytest.mark.install
-    def test_global_overrides_environment_markers(self):
+    def test_global_overrides_environment_markers(self, pypi):
         """Empty (unconditional) dependency should take precedence.
 
         If a dependency is specified without environment markers, it should
@@ -632,7 +659,7 @@ funcsigs = {version = "*", os_name = "== 'splashwear'"}
         APScheduler requires funcsigs only on Python 2, but since funcsigs is
         also specified as an unconditional dep, its markers should be empty.
         """
-        with PipenvInstance() as p:
+        with PipenvInstance(pypi=pypi) as p:
             with open(p.pipfile_path, 'w') as f:
                 contents = """
 [packages]
@@ -649,8 +676,11 @@ funcsigs = "*"
     @pytest.mark.install
     @pytest.mark.vcs
     @pytest.mark.tablib
-    def test_install_editable_git_tag(self, pip_src_dir, pypi):
-        with PipenvInstance(pypi=pypi) as p:
+    @needs_internet
+    def test_install_editable_git_tag(self, pip_src_dir):
+        # This uses the real PyPI since we need Internet to access the Git
+        # dependency anyway.
+        with PipenvInstance() as p:
             c = p.pipenv('install -e git+https://github.com/kennethreitz/tablib.git@v0.12.1#egg=tablib')
             assert c.return_code == 0
             assert 'tablib' in p.pipfile['packages']
@@ -923,9 +953,11 @@ flask = "==0.12.2"
 
     @pytest.mark.lock
     @pytest.mark.complex
-    def test_complex_lock_with_vcs_deps(self, pip_src_dir, pypi):
-
-        with PipenvInstance(pypi=pypi) as p:
+    @needs_internet
+    def test_complex_lock_with_vcs_deps(self, pip_src_dir):
+        # This uses the real PyPI since we need Internet to access the Git
+        # dependency anyway.
+        with PipenvInstance() as p:
             with open(p.pipfile_path, 'w') as f:
                 contents = """
 [packages]
@@ -955,14 +987,34 @@ requests = {git = "https://github.com/requests/requests", egg = "requests"}
 
     @pytest.mark.lock
     @pytest.mark.requirements
-    @pytest.mark.complex
-    @pytest.mark.maya
-    def test_complex_deps_lock_and_install_properly(self, pypi):
+    def test_lock_with_prereleases(self, pypi):
 
         with PipenvInstance(pypi=pypi) as p:
             with open(p.pipfile_path, 'w') as f:
                 contents = """
 [packages]
+sqlalchemy = "==1.2.0b3"
+
+[pipenv]
+allow_prereleases = true
+                """.strip()
+                f.write(contents)
+
+            c = p.pipenv('lock')
+            assert c.return_code == 0
+            assert p.lockfile['default']['sqlalchemy']['version'] == '==1.2.0b3'
+
+    @pytest.mark.lock
+    @pytest.mark.requirements
+    @pytest.mark.complex
+    @pytest.mark.maya
+    @needs_internet
+    def test_complex_deps_lock_and_install_properly(self):
+        # This uses the real PyPI because Maya has too many dependencies...
+        with PipenvInstance() as p:
+            with open(p.pipfile_path, 'w') as f:
+                contents = """
+[packages]
 maya = "*"
                 """.strip()
                 f.write(contents)
@@ -975,12 +1027,13 @@ maya = "*"
 
     @pytest.mark.extras
     @pytest.mark.lock
-    @pytest.mark.requirements
     @pytest.mark.complex
-    def test_complex_lock_deep_extras(self, pypi):
+    @needs_internet
+    def test_complex_lock_deep_extras(self):
         # records[pandas] requires tablib[pandas] which requires pandas.
+        # This uses the real PyPI; Pandas has too many requirements to mock.
 
-        with PipenvInstance(pypi=pypi) as p:
+        with PipenvInstance() as p:
             with open(p.pipfile_path, 'w') as f:
                 contents = """
 [packages]
@@ -988,12 +1041,12 @@ records = {extras = ["pandas"], version = "==0.5.2"}
                 """.strip()
                 f.write(contents)
 
+            c = p.pipenv('install')
+            assert c.return_code == 0
             c = p.pipenv('lock')
             assert c.return_code == 0
             assert 'tablib' in p.lockfile['default']
             assert 'pandas' in p.lockfile['default']
-            c = p.pipenv('install')
-            assert c.return_code == 0
 
     @pytest.mark.lock
     @pytest.mark.deploy
@@ -1009,9 +1062,10 @@ flask = "==0.12.2"
 pytest = "==3.1.1"
                 """.strip()
                 f.write(contents)
-
-            p.pipenv('lock')
-
+            c = p.pipenv('install')
+            assert c.return_code == 0
+            c = p.pipenv('lock')
+            assert c.return_code == 0
             with open(p.pipfile_path, 'w') as f:
                 contents = """
 [packages]
@@ -1025,6 +1079,7 @@ requests = "==2.14.0"
     @pytest.mark.install
     @pytest.mark.files
     @pytest.mark.urls
+    @needs_internet
     def test_urls_work(self, pypi):
 
         with PipenvInstance(pypi=pypi) as p:
@@ -1077,6 +1132,7 @@ requests = "==2.14.0"
             shutil.copy(source_path, os.path.join(p.path, file_name))
 
             c = p.pipenv('install {}'.format(file_name))
+            assert c.return_code == 0
             key = [k for k in p.pipfile['packages'].keys()][0]
             dep = p.pipfile['packages'][key]
 
@@ -1091,6 +1147,7 @@ requests = "==2.14.0"
     @pytest.mark.install
     @pytest.mark.files
     @pytest.mark.urls
+    @needs_internet
     def test_install_remote_requirements(self, pypi):
         with PipenvInstance(pypi=pypi) as p:
             # using a github hosted requirements.txt file
@@ -1158,10 +1215,8 @@ requests = "==2.14.0"
 url = 'https://${PYPI_USERNAME}:${PYPI_PASSWORD}@pypi.python.org/simple'
 verify_ssl = true
 name = 'pypi'
-
 [requires]
 python_version = '2.7'
-
 [packages]
 flask = "==0.12.2"
 """)