lydell/autoprefixer-brunch — pull request #5 by kenhkan (2013-12-04 16:22:17+00:00)
Title: Do not use unsupported styles

Somehow it recognizes all stylesheets as CSS. See https://github.com/brunch/sass-brunch/issues/35 for more detail. Excluding the stylesheets should be fine as Brunch pass those files through the preprocessors first anyway.