Fix portal management code to support non-default command completion tags for

portals using PORTAL_UTIL_SELECT strategy.  This is currently significant only
for FETCH queries, which are supposed to include a count in the tag.  Seems
it's been broken since 7.4, but nobody noticed before Knut Lehre.

src/backend/tcop/pquery.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.112 2007/01/05 22:19:39 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.113 2007/02/18 19:49:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -919,6 +919,8 @@ FillPortalStore(Portal portal)
 	PortalCreateHoldStore(portal);
 	treceiver = CreateDestReceiver(DestTuplestore, portal);
 
+	completionTag[0] = '\0';
+
 	switch (portal->strategy)
 	{
 		case PORTAL_ONE_RETURNING:
@@ -929,13 +931,11 @@ FillPortalStore(Portal portal)
 			 * tuplestore. Auxiliary query outputs are discarded.
 			 */
 			PortalRunMulti(portal, treceiver, None_Receiver, completionTag);
-			/* Override default completion tag with actual command result */
-			portal->commandTag = pstrdup(completionTag);
 			break;
 
 		case PORTAL_UTIL_SELECT:
 			PortalRunUtility(portal, linitial(portal->parseTrees),
-							 treceiver, NULL);
+							 treceiver, completionTag);
 			break;
 
 		default:
@@ -944,6 +944,10 @@ FillPortalStore(Portal portal)
 			break;
 	}
 
+	/* Override default completion tag with actual command result */
+	if (completionTag[0] != '\0')
+		portal->commandTag = pstrdup(completionTag);
+
 	(*treceiver->rDestroy) (treceiver);
 }