If you have access to the server / storage location, you can delete your original commit .
After that, you can do your commit again, but first add a new file. If this is a multi-user team, you need someone who upgraded to the new version, upgrade it to the old one, and then upgrade again.
This is not related, but the project I am working on has a "pre-commit-check" script that we run before committing. Among other things, it catches when we forget to add files.
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