Fix transition tables for wCTEs.

The original coding didn't handle this case properly; each separate
DML substatement needs its own set of transitions.

Patch by Thomas Munro

Discussion: https://postgr.es/m/CAL9smLCDQ%3D2o024rBgtD4WihzX8B3C6u_oSQ2K3%2BR5grJrV0bg%40mail.gmail.com

src/backend/executor/execReplication.c

@@ -419,6 +419,12 @@ ExecSimpleRelationInsert(EState *estate, TupleTableSlot *slot)
 		ExecARInsertTriggers(estate, resultRelInfo, tuple,
 							 recheckIndexes, NULL);
 
+		/*
+		 * XXX we should in theory pass a TransitionCaptureState object to the
+		 * above to capture transition tuples, but after statement triggers
+		 * don't actually get fired by replication yet anyway
+		 */
+
 		list_free(recheckIndexes);
 	}
 }