Remove forcing CI code path to use nt shell code path (#6072)

* Remove forcing CI code path to use nt shell code path and remove outdated comment

* Add news fragment

news/6072.bugfix.rst

@@ -0,0 +1 @@
+Remove logic that treats ``CI`` variable to use ``do_run_nt`` shell logic, as the original reasons for that patch were no longer valid.

pipenv/routines/shell.py

@@ -3,7 +3,6 @@ import subprocess
 import sys
 from os.path import expandvars
 
-from pipenv import environments
 from pipenv.utils.project import ensure_project
 from pipenv.utils.shell import cmd_list_to_shell, system_which
 from pipenv.vendor import click
@@ -99,9 +98,7 @@ def do_run(project, command, args, python=False, pypi_mirror=None):
         click.echo("Can't run script {0!r}-it's empty?", err=True)
     run_args = [project, script]
     run_kwargs = {"env": env}
-    # We're using `do_run_nt` on CI (even if we're running on a non-nt machine)
-    # as a workaround for https://github.com/pypa/pipenv/issues/4909.
-    if os.name == "nt" or environments.PIPENV_IS_CI:
+    if os.name == "nt":
         run_fn = do_run_nt
     else:
         run_fn = do_run_posix

tests/conftest.py

@@ -1,14 +1,4 @@
 import pytest
-import os
-
-# Note that we have to do this *before* `pipenv.environments` gets imported,
-# which is why we're doing it here as a side effect of importing this module.
-# CI=1 is necessary as a workaround for https://github.com/pypa/pipenv/issues/4909
-os.environ['CI'] = '1'
-
-def pytest_sessionstart(session):
-    import pipenv.environments
-    assert pipenv.environments.PIPENV_IS_CI
 
 
 @pytest.fixture()

tests/integration/test_run.py

@@ -41,8 +41,8 @@ multicommand = "bash -c \"cd docs && make html\""
         c = p.pipenv('run notfoundscript')
         assert c.returncode != 0
         assert c.stdout == ''
-        if os.name != 'nt':     # TODO: Implement this message for Windows.
-            assert 'not found' in c.stderr
+        if os.name != 'nt':
+            assert 'could not be found' in c.stderr
 
         project = Project()