tests/test-revlog-group-emptyiter.t

tests: run "cwd was removed" test only if cwd can actually be removed

On some platforms, cwd can't be removed. In which case, util.unlinkpath()
continues with no error since the failure of directory removal isn't critical.
So it doesn't make sense to run the test added by 90a6c18a7c1d on those
platforms. OTOH, we need to run the test in test-rebase-scenario-global.t
since the repository is referenced after that.

Issue1678: IndexError when pushing

setting up base repo
  $ hg init a
  $ cd a
  $ touch a
  $ hg ci -Am a
  adding a
  $ cd ..

cloning base repo
  $ hg clone a b
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd b

setting up cset to push
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ touch a
different msg so we get a clog new entry
  $ hg ci -Am b
  adding a
  created new head

pushing
  $ hg push -f ../a
  pushing to ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)

  $ cd ..