Allow directories in EXTRA_PATH_METADATA

Metadata applied to a directory will apply to all files under
it. In case of conflicts, child paths beat parent paths, so metadata
applied to `dir/subdir/file.md` will take precedence over that applied
to `dir/subdir`, which will take precedence over just `dir`.

pelican/tests/test_readers.py

@@ -273,6 +273,38 @@ class RstReaderTest(ReaderTest):
         }
         self.assertDictHasSubset(page.metadata, expected)
 
+    def test_article_extra_path_metadata_recurse(self):
+        parent = "TestCategory"
+        notparent = "TestCategory/article"
+        path = "TestCategory/article_without_category.rst"
+
+        epm = {
+            parent: {'epmr_inherit': parent,
+                     'epmr_override': parent, },
+            notparent: {'epmr_bogus': notparent},
+            path:   {'epmr_override': path, },
+            }
+        expected_metadata = {
+            'epmr_inherit': parent,
+            'epmr_override': path,
+            }
+
+        page = self.read_file(path=path, EXTRA_PATH_METADATA=epm)
+        self.assertDictHasSubset(page.metadata, expected_metadata)
+
+        # Make sure vars aren't getting "inherited" by mistake...
+        path = "article.rst"
+        page = self.read_file(path=path, EXTRA_PATH_METADATA=epm)
+        for k in expected_metadata.keys():
+            self.assertNotIn(k, page.metadata)
+
+        # Same, but for edge cases where one file's name is a prefix of
+        # another.
+        path = "TestCategory/article_without_category.rst"
+        page = self.read_file(path=path, EXTRA_PATH_METADATA=epm)
+        for k in epm[notparent].keys():
+            self.assertNotIn(k, page.metadata)
+
     def test_typogrify(self):
         # if nothing is specified in the settings, the content should be
         # unmodified