Minor fixes on tags sql file.

sql/tags.sql

@@ -1,4 +1,4 @@
-CREATE OR REPLACE LANGUAGE plpython3u;
+CREATE OR REPLACE LANGUAGE plpython2u;
 
 CREATE OR REPLACE FUNCTION unpickle (data text)
   RETURNS text[]
@@ -7,7 +7,4 @@ AS $$
     import pickle
 
     return pickle.loads(base64.b64decode(data))
-$$ LANGUAGE plpython3u IMMUTABLE;
-
-DROP INDEX IF EXISTS issues_unpickle_tags_index;
-CREATE INDEX issues_unpickle_tags_index ON issues_issue USING btree (unpickle(tags));
+$$ LANGUAGE plpython2u IMMUTABLE;