Fix dot handling in dist-info directory name

When searching for a matching dist-info directory, try to escape dots in
the name segment. This makes functions like distribution() able to accept
PEP 503 normalized names to locate a distribution's dist-info directory
if the distribution's name contains dots.

Author: uranusjr

importlib_metadata/__init__.py

@@ -473,7 +473,7 @@ def search(self, name):
         for child in self.children():
             n_low = child.lower()
             if (n_low in name.exact_matches
-                    or n_low.startswith(name.prefix)
+                    or n_low.replace('.', '_').startswith(name.prefix)
                     and n_low.endswith(name.suffixes)
                     # legacy case:
                     or self.is_egg(name) and n_low == 'egg-info'):

tests/fixtures.py

@@ -104,6 +104,21 @@ def setUp(self):
         build_files(DistInfoPkg.files, self.site_dir)
 
 
+class DistInfoPkgWithDot(OnSysPath, SiteDir):
+    files = {
+        "pkg.dot-1.0.0.dist-info": {
+            "METADATA": """
+                Name: pkg.dot
+                Version: 1.0.0
+                """,
+            },
+        }
+
+    def setUp(self):
+        super(DistInfoPkgWithDot, self).setUp()
+        build_files(DistInfoPkgWithDot.files, self.site_dir)
+
+
 class DistInfoPkgOffPath(SiteDir):
     def setUp(self):
         super(DistInfoPkgOffPath, self).setUp()

tests/test_api.py

@@ -22,6 +22,7 @@
 class APITests(
         fixtures.EggInfoPkg,
         fixtures.DistInfoPkg,
+        fixtures.DistInfoPkgWithDot,
         fixtures.EggInfoFile,
         unittest.TestCase):
 
@@ -41,6 +42,9 @@ def test_for_name_does_not_exist(self):
         with self.assertRaises(PackageNotFoundError):
             distribution('does-not-exist')
 
+    def test_for_name_containing_dot(self):
+        assert distribution('pkg-dot').metadata['Name'] == 'pkg.dot'
+
     def test_for_top_level(self):
         self.assertEqual(
             distribution('egginfo-pkg').read_text('top_level.txt').strip(),