Handles the case when reword is called and the `commit --amend` invokes
the pre-commit hook, when there is no stash the `git stash pop -q`
in that case leaves the rebase in an odd state.
Fixes by only calling the stash pop if changes were saved.
This pre-commit hook can be activated by copying or symlinking to
the .git/hooks directory
This particular commit hook is best suited for git versions < 1.8.2
The running of nosetests would be better suited for a push hook,
but those are not added until 1.8.2.
