tests/test-ssh-batch.t

revlog: move the details of revlog "v2" index inside revlog.utils.constants

the revlog module is quite large and this kind of format information would handy
for other module. So let us start to gather this information about the format in
a more appropriate place.

We update various reference to this information to use the new "source of truth"
in the process.

Differential Revision: https://phab.mercurial-scm.org/D10305

  $ 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$i; done) -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/$(pwd)/../a
  pulling from ssh://user@dummy/$TESTTMP/b/../a
  abort: unknown revision 'nosuchbookmark'
  [255]