tests/test-revlog-group-emptyiter.t

largefiles: handle logging from outside the repo

It's probably possible to refactor so that the 'if m._cwd' check isn't
necessary, but the False case is the typical case (i.e. run from the root of the
repo), and simpler to read.

An exact path to a largefile from outside the repo was previously ignored.

match.rel('.hglf') will handle figuring out both the correct '../' length to the
standin directory if inside the repo, or path/to/repo from outside, at the cost
of a pconvert() to keep the patterns using '/' on Windows.

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 ..