Mark an AP mention only if profile.finger is defined.

federation/entities/activitypub/models.py

@@ -885,11 +885,11 @@ class Note(Object, RawContentMixin):
         for mention in mentions:
             hrefs = []
             profile = get_profile_or_entity(fid=mention.href, remote_url=mention.href)
-            if profile and not profile.url:
-                # This should be removed when we are confident that the remote_url property
-                # has been populated for most profiles on the client app side.
+            if profile and not (profile.url and profile.finger):
+                # This should be removed when we are confident that the remote_url and
+                # finger properties have been populated for most profiles on the client app side.
                 profile = retrieve_and_parse_profile(profile.id)
-            if profile:
+            if profile and profile.finger:
                 hrefs.extend([profile.id, profile.url])
             else:
                 continue