It would be easier:
git fetch (brings everything locally)git cherry-pick <SHA1 of the right commit>
Once the choice is made, you can make a cherry-pick commit that fixes the error (it should be part of git log origin/xxx, with xxxis the branch where the error correction was fixed on the GitHub side)
, master, push git GitHub master.
:
git remote add otherfork /url/to/other/fork
git fetch otherfork
git cherry-pick <commit>