fix: correct some bug introduce with typing

yams/schema.py

@@ -570,9 +570,7 @@ class EntitySchema(PermissionMixIn, ERSchema):
         """return metadata's relation schema if this entity has the given
         `metadata` field for the given `attribute` attribute
         """
-        return self._subject_relations.get(
-            self.schema.relation_schema_for("%s_%s" % (attribute, metadata))
-        )
+        return self._subject_relations.get("%s_%s" % (attribute, metadata))
 
     @deprecation.argument_renamed(old_name="attr", new_name="attribute")
     def is_metadata(self, attribute) -> Optional[Tuple[str, str]]:
@@ -1480,7 +1478,9 @@ class Schema:
             ] = []
 
             for a_b, relation_definition in relation.relation_definitions.items():
-                if a_b[0] == old_name:
+                if a_b == (old_name, old_name):
+                    to_rename.append((a_b, (new_name, new_name), relation_definition))
+                elif a_b[0] == old_name:
                     to_rename.append((a_b, (new_name, a_b[1]), relation_definition))
                 elif a_b[1] == old_name:
                     to_rename.append((a_b, (a_b[0], new_name), relation_definition))