In pg_upgrade, because toast table names can be mismatched with the heap

oid on 8.4, modify the toast name comparison test to only apply to old
9.0+ servers.  (The test was previously 8.4+.)

Backpatch to 9.1.X.

contrib/pg_upgrade/info.c

@@ -57,12 +57,15 @@ gen_db_file_maps(DbInfo *old_db, DbInfo *new_db,
 				   old_db->db_name, old_rel->reloid, new_rel->reloid);
 
 		/*
-		 * In pre-8.4, TOAST table names change during CLUSTER;  in >= 8.4
-		 * TOAST relation names always use heap table oids, hence we cannot
-		 * check relation names when upgrading from pre-8.4.
+		 * TOAST table names initially match the heap pg_class oid.
+		 * In pre-8.4, TOAST table names change during CLUSTER; in pre-9.0,
+		 * TOAST table names change during ALTER TABLE ALTER COLUMN SET TYPE.
+		 * In >= 9.0, TOAST relation names always use heap table oids, hence
+		 * we cannot check relation names when upgrading from pre-9.0.
+		 * Clusters upgraded to 9.0 will get matching TOAST names.
 		 */
 		if (strcmp(old_rel->nspname, new_rel->nspname) != 0 ||
-			((GET_MAJOR_VERSION(old_cluster.major_version) >= 804 ||
+			((GET_MAJOR_VERSION(old_cluster.major_version) >= 900 ||
 			  strcmp(old_rel->nspname, "pg_toast") != 0) &&
 			 strcmp(old_rel->relname, new_rel->relname) != 0))
 			pg_log(PG_FATAL, "Mismatch of relation names in database \"%s\": "