Fix oversight in new EvalPlanQual logic: the second loop over the ExecRowMark

list in ExecLockRows() forgot to allow for the possibility that some of the
rowmarks are for child tables that aren't relevant to the current row.
Per report from Kenichiro Tanaka.

src/backend/executor/nodeLockRows.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeLockRows.c,v 1.5 2010/07/12 17:01:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeLockRows.c,v 1.6 2010/07/28 17:21:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -195,6 +195,13 @@ lnext:
 			HeapTupleData tuple;
 			Buffer		buffer;
 
+			/* ignore non-active child tables */
+			if (!ItemPointerIsValid(&(erm->curCtid)))
+			{
+				Assert(erm->rti != erm->prti);	/* check it's child table */
+				continue;
+			}
+
 			if (EvalPlanQualGetTuple(&node->lr_epqstate, erm->rti) != NULL)
 				continue;		/* it was updated and fetched above */