Fix crash when trying to display a NOTIFY rule action.

Fixes oversight in commit 2ffa740be9.
Per report from Josh Kupershmidt.

I think we've broken this case before, so let's add a regression test
this time.

src/backend/utils/adt/ruleutils.c

@@ -2564,14 +2564,19 @@ set_deparse_for_query(deparse_namespace *dpns, Query *query,
 		dpns->rtable_columns = lappend(dpns->rtable_columns,
 									   palloc0(sizeof(deparse_columns)));
 
-	/* Detect whether global uniqueness of USING names is needed */
-	dpns->unique_using = has_unnamed_full_join_using((Node *) query->jointree);
+	/* If it's a utility query, it won't have a jointree */
+	if (query->jointree)
+	{
+		/* Detect whether global uniqueness of USING names is needed */
+		dpns->unique_using =
+			has_unnamed_full_join_using((Node *) query->jointree);
 
-	/*
-	 * Select names for columns merged by USING, via a recursive pass over the
-	 * query jointree.
-	 */
-	set_using_names(dpns, (Node *) query->jointree);
+		/*
+		 * Select names for columns merged by USING, via a recursive pass over
+		 * the query jointree.
+		 */
+		set_using_names(dpns, (Node *) query->jointree);
+	}
 
 	/*
 	 * Now assign remaining column aliases for each RTE.  We do this in a

src/test/regress/expected/rules.out

@@ -2573,6 +2573,7 @@ select * from rules_log;
  11 |  13 | new
 (12 rows)
 
+create rule r3 as on delete to rules_src do notify rules_src_deletion;
 \d+ rules_src
                       Table "public.rules_src"
  Column |  Type   | Modifiers | Storage | Stats target | Description 
@@ -2584,6 +2585,9 @@ Rules:
     ON UPDATE TO rules_src DO  INSERT INTO rules_log (f1, f2, tag) VALUES (old.f1,old.f2,'old'::text), (new.f1,new.f2,'new'::text)
     r2 AS
     ON UPDATE TO rules_src DO  VALUES (old.f1,old.f2,'old'::text), (new.f1,new.f2,'new'::text)
+    r3 AS
+    ON DELETE TO rules_src DO 
+ NOTIFY rules_src_deletion
 Has OIDs: no
 
 --

src/test/regress/sql/rules.sql

@@ -970,6 +970,7 @@ create rule r2 as on update to rules_src do also
 update rules_src set f2 = f2 / 10;
 select * from rules_src;
 select * from rules_log;
+create rule r3 as on delete to rules_src do notify rules_src_deletion;
 \d+ rules_src
 
 --