mxcl/homebrew — pull request #12020 by 2bits (2012-05-02 23:56:22+00:00)
Title: ffmpeg: use linked_keg for x264 check

ffmpeg when built as head checks if x264 is installed using
`Formula.factory.installed?` that won't find x264 stable.
Switch from `.installed?` to `linked_keg.exist?` because
it will find x264 whether it's installed as head or stable.

Fixes #11996