MFC r337536:

MFC r337536:
  If -q flag is specified, do not complain when we are trying to delete
  nonexistent NAT instance or nonexistent rule.

  This allows execute batched `delete` commands and do not fail when
  found nonexistent rule.

MFC r337574:
  Restore the behaviour changed in r337536, when bad `ipfw delete` command
  returns error.

  Now -q option only makes it quiet. And when -f flag is specified, the
  command will ignore errors and continue executing with next batched
  command.

Obtained from:	Yandex LLC
Sponsored by:	Yandex LLC