mozilla/rust — pull request #7948 by roysc (2013-07-21 21:17:47+00:00)
Title: Make `rust-mode` derive from `prog-mode` if available

This let rust-mode be classified as a programming mode, which is only relevant to Emacs 24.x. This way, for one thing, `prog-mode-hook`s will be run when entering `rust-mode`.