mq: add qdelete --forget option
This removes an applied patch from the series and status files without
popping it. It is useful when an mq patch has been applied upstream.
abort: repository a not found!
255
abort: error: Connection refused
255
abort: repository a not found!
255
abort: destination '../a' already exists
255
abort: repository a not found!
255
abort: destination 'q' already exists