Sorry, that will not be actual answer.
There may be some way, but actually I don't see much point to it. Committing is rather light. There's nothign wrong in committing a completely temporary or broken files. Until you push it to public, it's all your local storage. Just create a new branch, commit to it, then at some point of time you can delete that branch, even immediatelly. The only thing you must be careful is to not push that branch to public repo. The biggest plus in it is that, during commit, you will be able to selectively pick what files you want to include. It will allow you to filter out any unwanted binaries, archives, etc - and at very fine details. It's really much more usable than trying to filter them by bash
and similar.
So, for me, if you are building packages, then you really want to commit. Just because at some point of time in future you will need to check what were the original files. Or revert to it. That's exactly what branches and whole repository is: marking and remembering some files in some state. Repository is not just for keeping "release code". It is for keeping everything relevant that you needed at any point of time, in the same exact state as it was back then.
Therefore, I'd even recommend true branching for those builds/packagings. Not stash. Stash is something temporary, meant to evaporate quickly. You get a hash for that, but you can very easily delete that whole branch/stash/revision. That would exactly annihilate the essence of versioning. You will put it into git, just to delete it.
With use of normal branches and normal commits, at any future time you will be able to review or recreate any RPM you have built at any time in the history. IMHO, that's huge plus.
gitzip
in your folder. – Amathiste