pg_upgrade: work around recent test failures

We currently have a bug where a heap partition that is exchanged out of
the partition hierarchy is not given an array type. When this table is
restored in the new database, it will be given an array type -- but
there will be no preassigned OID for it, so it'll steal one from the
pool. If some other object collides with that stolen OID, upgrade will
fail.

Some recent test additions appear to have shifted OIDs around enough to
expose this latent issue, and it's not immediately clear how to fix it,
so add this to the drop script for now so the pipeline isn't blocked.
Co-authored-by: NTaylor Vesely <tvesely@pivotal.io>

contrib/pg_upgrade/test_gpdb_pre.sql

@@ -44,6 +44,46 @@ $$ LANGUAGE plpgsql;
 SELECT drop_indexes();
 DROP FUNCTION drop_indexes();
 
+-- We currently have a bug where a heap partition that is exchanged out of the
+-- partition hierarchy is not given an array type. When this table is restored
+-- in the new database, it will be given an array type -- but there will be no
+-- preassigned OID for it, so it'll steal one from the pool. If some other
+-- object collides with that stolen OID, upgrade will fail.
+CREATE OR REPLACE FUNCTION drop_heaps_without_array_types() RETURNS void AS $$
+DECLARE
+	broken_table RECORD;
+	sql TEXT;
+BEGIN
+	FOR broken_table IN
+		SELECT n.nspname, c.relname
+		  FROM pg_class c
+		  JOIN pg_namespace n ON (n.oid = c.relnamespace)
+		  JOIN pg_type t ON (t.typrelid = c.oid)
+		  LEFT JOIN pg_type arr ON (arr.typelem = t.oid)
+		  LEFT JOIN pg_partition_rule pr ON (pr.parchildrelid = c.oid)
+		WHERE
+		  -- heap relations only
+		  c.relstorage = 'h' AND c.relkind = 'r'
+		  -- that aren't subpartitions
+		  AND pr.oid IS NULL
+		  -- and that aren't catalog tables
+		  AND n.nspname NOT IN ('pg_catalog', 'pg_toast', 'pg_aoseg',
+							    'pg_bitmapindex', 'gp_toolkit', 'information_schema')
+		  -- with no array type
+		  AND arr.oid IS NULL
+	LOOP
+		sql := 'DROP TABLE ' || quote_ident(broken_table.nspname) || '.' || quote_ident(broken_table.relname) || ' CASCADE';
+
+		RAISE NOTICE '%', sql;
+		EXECUTE sql;
+	END LOOP;
+	RETURN;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT drop_heaps_without_array_types();
+DROP FUNCTION drop_heaps_without_array_types();
+
 -- This one's interesting:
 --    No match found in new cluster for old relation with OID 173472 in database "regression": "public.sales_1_prt_bb_pkey" which is an index on "public.newpart"
 --    No match found in old cluster for new relation with OID 556718 in database "regression": "public.newpart_pkey" which is an index on "public.newpart"