Revert "Simplify bsdmake wrapper"

Fixes #34713.

This reverts commit e4461afd36f04b1cd3cf56ec0636202150ce0570.
Simplify bsdmake wrapper, take 2
Stop supporting hg found in share/python
Download strategies should return a Pathname from cached_location
Provide VCSDownloadStrategy#head?
sdl: fixing dom is a moron

Deals with the issue flagged up in [this
commit](https://github.com/Homebrew/homebrew/commit/0d6d0213dc4cc406cdfd
cb5ba742b361a0ab2210). Should have caught this at the time. I am an
idiot.
sdl: update 1.2.15 bottle.