tests/test-mq-qsave.t

discovery: only calculate closed branches if required

The number of new closed branches is required for printing in error message. So
let's only calculate them if we need to print error about new branches.

Differential Revision: https://phab.mercurial-scm.org/D6314

  $ 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