Remove vendored packages.

Pull request pypa/distutils#288 from abravalheri

Author: jaraco

conftest.py

@@ -16,11 +16,6 @@
     ])
 
 
-collect_ignore_glob = [
-    'distutils/_vendor/**/*',
-]
-
-
 @pytest.fixture
 def save_env():
     orig = os.environ.copy()