Disable import of setuptools for sdist builds. Fixes pypa#4264 and pypa/setuptools#951.

Author: jaraco

CHANGES.txt

@@ -1,3 +1,9 @@
+** 9.0.2 (2017-02-??) **
+
+* Only check that setuptools appears to be installed but no longer test
+  the import before invoking a sdist build (:issue:`4264`).
+
+
 **9.0.1 (2016-11-06)**
 
 * Correct the deprecation message when not specifying a --format so that it

pip/req/req_install.py

@@ -383,17 +383,10 @@ def setup_py_dir(self):
     @property
     def setup_py(self):
         assert self.source_dir, "No source dir for %s" % self
-        try:
-            import setuptools  # noqa
-        except ImportError:
-            if get_installed_version('setuptools') is None:
-                add_msg = "Please install setuptools."
-            else:
-                add_msg = traceback.format_exc()
-            # Setuptools is not available
-            raise InstallationError(
-                "Could not import setuptools which is required to "
-                "install from a source distribution.\n%s" % add_msg
+        if get_installed_version('setuptools') is None:
+            raise InstallationError("Setuptools is required to install "
+                "from a source distribution, but none was found. Please "
+                "install setuptools."
             )
 
         setup_py = os.path.join(self.setup_py_dir, 'setup.py')

tests/functional/test_install.py

@@ -28,38 +28,13 @@ def test_without_setuptools(script, data):
         expect_error=True,
     )
     assert (
-        "Could not import setuptools which is required to install from a "
-        "source distribution."
+        "Setuptools is required to install from a source distribution, but "
+        "none was found."
         in result.stderr
     )
     assert "Please install setuptools" in result.stderr
 
 
-def test_with_setuptools_and_import_error(script, data):
-    # Make sure we get an ImportError while importing setuptools
-    setuptools_init_path = script.site_packages_path.join(
-        "setuptools", "__init__.py")
-    with open(setuptools_init_path, 'a') as f:
-        f.write('\nraise ImportError("toto")')
-
-    result = script.run(
-        "python", "-c",
-        "import pip; pip.main(["
-        "'install', "
-        "'INITools==0.2', "
-        "'-f', '%s', "
-        "'--no-binary=:all:'])" % data.packages,
-        expect_error=True,
-    )
-    assert (
-        "Could not import setuptools which is required to install from a "
-        "source distribution."
-        in result.stderr
-    )
-    assert "Traceback " in result.stderr
-    assert "ImportError: toto" in result.stderr
-
-
 def test_pip_second_command_line_interface_works(script, data):
     """
     Check if ``pip<PYVERSION>`` commands behaves equally