tests/test-mq-qsave.t

push: move `incoming` into the push object

The fact that there is some unknown changes on remote one of the result of
discovery. It is then used by some push validation logic.

We move it in the object to be able to extract the said logic.

  $ 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