Homebrew/homebrew — pull request #26822 by g-nix (2014-02-18 20:28:01+00:00)
Title: Fix hg: no recusive self-dep for HEAD, manpages install.

So, obviously I had to get a little creative here. But keep in mind how `--HEAD` was implemented before this.
I'll let y'all have at it first rather than give a whole long spiel.