New review comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/29120#discussion_r584357334

Comment:
This needs a comment on why, though it is kinda acceptable, given that they delete old tarballs :(

Maybe we could hardcode the commit for the given tag? Instead of pulling the tag directly. Not sure that's supported or if it'd make the clone too big.