small pgsql fix.

if we fail at rolling back an in-error transaction on a connection
just remove that connection and go back to rescanning rather then
returning an error to the caller, there may be more functional
connections in the pipeline.

src/pgsql.c

@@ -467,7 +467,6 @@ rescan:
 				kore_pgsql_cleanup(rollback);
 				kore_free(rollback);
 				pgsql_conn_cleanup(conn);
-				return (NULL);
 			}
 
 			goto rescan;