CommitController uses `@base` to shorten the list of files to commit
to relative names, but that variable is never set (except in
SCM::Git.SubmoduleBase, but that isn't relevant here).
The `shorten` method continues to work when inside a project as is
tries to use `$TM_PROJECT_DIRECTORY` anyway, but otherwise, git add
and git commit are called with the absolute paths to the changed files
and throw errors.
To fix this, we can call shorten with `git.git_base`.
A patch for this can be found at: <http://pastie.caboo.se/167301>
Cheers and thanks for the awesome bundle,
Martin