tests/test-update-renames.t

posix: fix split() for the case where the path is at the root of the filesystem

posixpath.split() strips '/' from the dirname *unless it is the root*. This
patch reproduces this behavior in posix.split(). The old behavior causes a
crash when creating a file at the root of the repo with localrepo.wfile()
when the repo is at the root of the filesystem.

Test update logic when there are renames

Update with local changes across a file rename

  $ hg init

  $ echo a > a
  $ hg add a
  $ hg ci -m a

  $ hg mv a b
  $ hg ci -m rename

  $ echo b > b
  $ hg ci -m change

  $ hg up -q 0

  $ echo c > a

  $ hg up
  merging a and b to b
  warning: conflicts during merge.
  merging b incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]