mxcl/homebrew — pull request #14987 by halostatue (2012-09-17 17:28:41+00:00)
Title: Fixing the_silver_searcher install failure.

This formula assumes that the aclocal include directory is /usr/local/share/aclocal; this is not true if you have installed homebrew into a different location (as I have done).

Using HOMEBREW_PREFIX instead of assuming /usr/local is the correct fix.