Distribution._normalized_name for .egg-info has 'egg' in it.

[jaraco]

In jaraco/keyring#526 (comment), I learned that _normalized_name for .egg-info distributions is resolving to <pkg>.egg and thus is unique against the same package with .dist-info, failing the expectation that entry points for a given package are loaded only once.

[jaraco]

I've managed to put together a test that captures the failure, but the test passes on 4.11.4, failing on 4.11.3 and earlier only:

 importlib_metadata afdb973b3e $ git diff --cached
diff --git a/tests/test_main.py b/tests/test_main.py
index 215662dd04..8583146f2a 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -121,6 +121,23 @@ class NameNormalizationTests(fixtures.OnSysPath, fixtures.SiteDir, unittest.Test
 
         assert len(after) == len(before)
 
+    def test_egg_and_dist_same(self):
+        """
+        Two distributions varying only by metadata style should resolve
+        as the same.
+        """
+        dist_info = {'storytime.dist-info': dict(METADATA='VERSION: 1.0\n')}
+        fixtures.build_files(dist_info, self.site_dir)
+        egg_info = {'storytime.egg-info': dict(METADATA='VERSION: 1.0\n')}
+        fixtures.build_files(egg_info, self.site_dir)
+        dists = [
+            dist
+            for dist in distributions()
+            if dist._normalized_name.startswith('storytime')
+        ]
+        assert len(dists) == 2
+        assert all(dist._normalized_name == 'storytime' for dist in dists)
+

[jaraco]

Indeed, the issue is a duplicate of #377.