tests/test-mq-qsave.t

blackbox: flush output file descriptor

Without this, when there are multiple ui views, each blackbox
will have its own file handle, and the logging will be in
a really bad order.

Also, because of the way blackbox works, it never closes its
file handles, which means the last output before exit is
often lost.

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH

  $ hg init

  $ echo 'base' > base
  $ hg ci -Ambase
  adding base

  $ hg qnew -mmqbase mqbase

  $ hg qsave
  $ hg qrestore 2
  restoring status: hg patches saved state