Keep commit message when a hooks fail

[steinybot]

I love how overcommit helps our team to write good commit messages however it is really annoying when one spends a while writing a commit message only to have the hook fail and have the message lost.

It would be great if there was a way to keep the commit message when a hook fails, or better yet, allow the message to be edited again.

[sds]

Would love to have someone dig in and submit a pull request adding support for this. Thanks!