New review comment by astralchan on void-packages repository

https://github.com/void-linux/void-packages/pull/42687#discussion_r1133174298

Comment:
I like evaluating expressions then substituting them. It makes it simpler for me to maintain. Specifically, if I see a substitution inside expanded in `distfiles`, I would need to mentally expand `/./_` in the middle of a URL. This visually is confusing to me, the maintainer. If I see `_version`, I can expand to see that it would expand to `r3_9_1` then substitute that. Those are the mechanisms by which it makes it more maintainable for me.