NixOS/nixpkgs — pull request #2455 by bjornfor (2014-04-30 19:57:20+00:00)
Title: More helpful message when refusing to evaluate "broken" package

A "broken" package is one where either "meta.broken = true" or build
platform != meta.platforms.

NOTE: I haven't tested this yet, I just copied the message from the "allowUnfree" block (just above this hunk) and changed the text as needed.