lib-sieve: Never return TRUE from sieve_multiscript_will_discard() wh…

…en status is not successful.

Errors will trigger an implicit keep, not discard.

src/lib-sieve/sieve.c

@@ -730,7 +730,7 @@ bool sieve_multiscript_run
 bool sieve_multiscript_will_discard
 (struct sieve_multiscript *mscript)
 {
-	return ( !mscript->active &&
+	return ( !mscript->active && mscript->status == SIEVE_EXEC_OK &&
 		!sieve_result_executed_delivery(mscript->result) );
 }