ITS#7687: password modify can muck with controls (quick fix)

servers/slapd/back-ldap/chain.c

@@ -196,12 +196,13 @@ chaining_control_remove(
 	 * added by the chain overlay, so it's the only one we explicitly 
 	 * free */
 	if ( op->o_ctrls != oldctrls ) {
-		assert( op->o_ctrls != NULL );
-		assert( op->o_ctrls[ 0 ] != NULL );
+		if ( op->o_ctrls != NULL ) {
+			assert( op->o_ctrls[ 0 ] != NULL );
 
-		free( op->o_ctrls );
+			free( op->o_ctrls );
 
-		op->o_chaining = 0;
+			op->o_chaining = 0;
+		}
 		op->o_ctrls = oldctrls;
 	}