tests/test-ssh-batch.t

undo-files: also remove the undo.backupfiles

The undo.backupfiles is dealt is directly managed by the transaction instead of
going through the `localrepo.undofiles`. We start doing minimal management for
it before using `cleanup_undo_files` on more situation. Proper handling of it
is an intermediate goal of this series.

  $ hg init a
  $ cd a
  $ touch a; hg commit -qAm_
  $ hg bookmark $(for i in $($TESTDIR/seq.py 0 20); do echo b$i; done)
  $ hg clone . ../b -q
  $ cd ../b

Checking that when lookup multiple bookmarks in one go, if one of them
fails (thus causing the sshpeer to be stopped), the errors from the
further lookups don't result in tracebacks.

  $ hg pull -r b0 -r nosuchbookmark $(for i in $($TESTDIR/seq.py 1 20); do echo -r b$i; done) ssh://user@dummy/$(pwd)/../a
  pulling from ssh://user@dummy/$TESTTMP/b/../a
  abort: unknown revision 'nosuchbookmark'
  [255]