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 failed!

  0 files updated, 0 files merged, 0 files removed, 1 files unresolved

  use 'hg resolve' to retry unresolved file merges

  [1]

  $ cd ..