I\'m attempting to re-install Ruby 1.9.3 with a patch that will allow me to use ruby-debug.
When following the instructions and running
rvm reinstall
I had a similar problem, but because Homebrew moved away from the Cellar directory, but for some reasons binaries of this package were still there.
I reinstalled autoconf with the following command and autoreconf is in the right PATH now: brew reinstall autoconf
brew reinstall autoconf