emit a single warning for overwriting files

Rather than emitting a separate warning for each owner, produce one
warning with all of the other owner names in the message.

Signed-off-by: Doug Hellmann <[email protected]>

Author: dhellmann

src/pip/_internal/operations/install/wheel.py

@@ -30,6 +30,7 @@
 from pip._internal.models.direct_url import DIRECT_URL_METADATA_NAME, DirectUrl
 from pip._internal.utils.deprecation import deprecated
 from pip._internal.utils.filesystem import adjacent_tmp_file, replace
+from pip._internal.utils.messages import oxford_comma_join
 from pip._internal.utils.misc import captured_stdout, ensure_dir, hash_file
 from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
@@ -416,15 +417,18 @@ def _report_file_owner_conflicts(
                 # There are no other owners for this file.
                 continue
             destfile = os.path.join(lib_dir, basedir, f)
-            for owner in files_from_other_owners[partial_src]:
-                deprecated(
-                    reason=('Overwriting or removing {} for {} '
-                            'which is also owned by {}'.format(
-                                destfile, name, owner)),
-                    replacement=None,
-                    gone_in="21.0",
-                    issue="4625",
-                )
+            deprecated(
+                reason=(
+                    'Overwriting or removing {} for {} '
+                    'which is also owned by {}'.format(
+                        destfile, name,
+                        oxford_comma_join(
+                            sorted(files_from_other_owners[partial_src])),
+                    )),
+                replacement=None,
+                gone_in="21.0",
+                issue=4625,
+            )
 
 
 def install_unpacked_wheel(

tests/functional/test_install_wheel.py

@@ -756,9 +756,5 @@ def test_report_file_owner_conflicts_multiple(script, tmpdir):
     assert msg in result.stderr
 
     msg = 'Overwriting or removing {} for {} which is also owned by {}'.format(
-        full_path, 'wheel3', 'wheel1 1.0')
-    assert msg in result.stderr
-
-    msg = 'Overwriting or removing {} for {} which is also owned by {}'.format(
-        full_path, 'wheel3', 'wheel2 2.0')
+        full_path, 'wheel3', 'wheel1 1.0 and wheel2 2.0')
     assert msg in result.stderr