fix requirementslib issue

pipenv/core.py

@@ -823,8 +823,8 @@ def do_install_dependencies(
             click.echo(
                 crayons.normal(fix_utf8("Installing dependencies from Pipfile…"), bold=True)
             )
-            # skip_lock should completely bypass the lockfile (broken in 4dac1676)
-            lockfile = project.get_or_create_lockfile(from_pipfile=True)
+        # skip_lock should completely bypass the lockfile (broken in 4dac1676)
+        lockfile = project.get_or_create_lockfile(from_pipfile=True)
     else:
         lockfile = project.get_or_create_lockfile()
         if not bare:
@@ -851,7 +851,6 @@ def do_install_dependencies(
             "\n".join(sorted(deps))
         )
         sys.exit(0)
-
     if concurrent:
         nprocs = PIPENV_MAX_SUBPROCESS
     else:

pipenv/vendor/requirementslib/models/setup_info.py

@@ -1580,29 +1580,7 @@ class SetupInfo(object):
 
     def build_wheel(self):
         # type: () -> S
-        if not self.pyproject.exists():
-            build_requires = ", ".join(['"{0}"'.format(r) for r in self.build_requires])
-            self.pyproject.write_text(
-                six.text_type(
-                    """
-[build-system]
-requires = [{0}]
-build-backend = "{1}"
-                """.format(
-                        build_requires, self.build_backend
-                    ).strip()
-                )
-            )
-        return build_pep517(
-            self.base_dir,
-            self.extra_kwargs["build_dir"],
-            config_settings=self.pep517_config,
-            dist_type="wheel",
-        )
-
-    # noinspection PyPackageRequirements
-    def build_sdist(self):
-        # type: () -> S
+        need_delete = False
         if not self.pyproject.exists():
             if not self.build_requires:
                 build_requires = '"setuptools", "wheel"'
@@ -1621,12 +1599,49 @@ build-backend = "{1}"
                     ).strip()
                 )
             )
-        return build_pep517(
+            need_delete = True
+        result = build_pep517(
+            self.base_dir,
+            self.extra_kwargs["build_dir"],
+            config_settings=self.pep517_config,
+            dist_type="wheel",
+        )
+        if need_delete:
+            self.pyproject.unlink()
+        return result
+
+    # noinspection PyPackageRequirements
+    def build_sdist(self):
+        # type: () -> S
+        need_delete = False
+        if not self.pyproject.exists():
+            if not self.build_requires:
+                build_requires = '"setuptools", "wheel"'
+            else:
+                build_requires = ", ".join(
+                    ['"{0}"'.format(r) for r in self.build_requires]
+                )
+            self.pyproject.write_text(
+                six.text_type(
+                    """
+[build-system]
+requires = [{0}]
+build-backend = "{1}"
+                """.format(
+                        build_requires, self.build_backend
+                    ).strip()
+                )
+            )
+            need_delete = True
+        result = build_pep517(
             self.base_dir,
             self.extra_kwargs["build_dir"],
             config_settings=self.pep517_config,
             dist_type="sdist",
         )
+        if need_delete:
+            self.pyproject.unlink()
+        return result
 
     def build(self):
         # type: () -> "SetupInfo"