Git driver silently fails to push on retry

[ljfranklin]

We had a build CI in fail to push the bump commit using the git driver even though the put step went green. We think this is due to the retry logic here. In that event that the git commit succeeds but the git push fails, the method is retried but will exit without pushing as it thinks there is nothing to commit.

We also noticed in this that the get step does not do any sanity checking to make sure that the version passed to it via the request matches the version that's located on disk. If this mismatch were caught, we would have seen it fail in the implicit get afterwards. We think the fact that it stopped looking at disk happened in this commit. Adding this behavior might be tricky if you are dealing with storage that's eventually consistent (like S3).

[ljfranklin]

Our original theory was off as on retry the resource runs reset --hard which should clear out any commits which haven't been pushed. Opened a PR here to add additional logging to help us debug this in the future.