Deprecate uninstalling distutils installed projects

pip/req/req_install.py

@@ -6,6 +6,7 @@ import re
 import shutil
 import sys
 import tempfile
+import warnings
 import zipfile
 
 from distutils.util import change_root
@@ -32,6 +33,7 @@ from pip.utils import (
     dist_in_usersite, dist_in_site_packages, egg_link_path, make_path_relative,
     call_subprocess, read_text_file, FakeFile, _make_build_dir,
 )
+from pip.utils.deprecation import RemovedInPip8Warning
 from pip.utils.logging import indent_log
 from pip.req.req_uninstall import UninstallPathSet
 from pip.vcs import vcs
@@ -600,6 +602,13 @@ exec(compile(
                     paths_to_remove.add(path + '.pyc')
 
         elif distutils_egg_info:
+            warnings.warn(
+                "Uninstalling a distutils installed project ({0}) has been "
+                "deprecated and will be removed in a future version. This is "
+                "due to the fact that uninstalling a distutils project will "
+                "only partially uninstall the project.".format(self.name),
+                RemovedInPip8Warning,
+            )
             paths_to_remove.add(distutils_egg_info)
 
         elif dist.location.endswith('.egg'):