I'm currently figuring out how to do this properly, these are just notes, so I don't have to find everything again.
https://stackoverflow.com/questions/40757246/git-status-and-git-diff-empty-after-failed-git-am
git remote add patch-origin git fetch patch-origin
git format-patch -1
git am --ignore-whitespace --ignore-space-change -3 <
git am --continue
git mergetool