Switched Branch After .gitignore and lost .gitinored files

You can do this by using git reflog --all to get the SHA code from when the Github App automatically stashed your ignored files before switching to the other branch. See https://stackoverflow.com/a/8865242/2970321.

For example, I fetched a pull request (/pr/364) using the app (SHA 2ba129d). Before I switched back to gh-pages, it stashed my ignored files (SHA 36edfc6).

So to recover, all I needed to do was:

git checkout 36edfc6

My files magically reappeared, and I was able to safely stash them manually somewhere else before switching back to gh-pages again.