Multi-commit PRs

[realaravinth]

Our current PR workflow looks like this:

1. Get patch at https://github.com/{owner}/{repo}/pull/{id}.patch
2. Process .fignore
3. Send to upstrea interface
4. Upstream interface applies patch and sends PR to upstream repo

If the PR was made up of multiple commits, we are losing valuable commit messages. I think we can accommodate multi-commit PRs by generating a sequence of patches for each commit of the PR.