brew --config

HOMEBREW_VERSION: 0.9.4
ORIGIN: https://github.com/mxcl/homebrew
HEAD: e76ae4e896d12e3fde7fd0c06eafe846e9160ea2
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CELLAR: /usr/local/Cellar
CPU: quad-core 64-bit sandybridge
OS X: 10.8.4-x86_64
Xcode: 4.6.3
CLT: 4.6.0.0.1.1365549073
GCC-4.2: build 5666
LLVM-GCC: build 2336
Clang: 4.2 build 425
X11: 2.7.4 => /opt/X11
System Ruby: 1.8.7-358
Perl: /usr/bin/perl
Python: /usr/local/bin/python => /usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/bin/python2.7
Ruby: /Users/fxposter/.rvm/rubies/ruby-1.9.3-p327/bin/ruby

brew doctor

Warning: Unbrewed dylibs were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected dylibs:
    /usr/local/lib/libusb-1.0.0.dylib
Error: undefined method `head' for #<SoftwareSpec:0x105945c40>
Please report this bug:
    https://github.com/mxcl/homebrew/wiki/troubleshooting
/usr/local/Library/Formula/sphinx.rb:24
/usr/local/Library/Homebrew/formula.rb:722:in `instance_eval'
/usr/local/Library/Homebrew/formula.rb:722:in `resource'
/usr/local/Library/Formula/sphinx.rb:23
/usr/local/Library/Homebrew/formulary.rb:40:in `require'
/usr/local/Library/Homebrew/formulary.rb:40:in `klass'
/usr/local/Library/Homebrew/formulary.rb:90:in `get_formula'
/usr/local/Library/Homebrew/formulary.rb:175:in `factory'
/usr/local/Library/Homebrew/formula.rb:432:in `factory'
/usr/local/Library/Homebrew/formula.rb:384:in `installed'
/usr/local/Library/Homebrew/formula.rb:382:in `map'
/usr/local/Library/Homebrew/formula.rb:382:in `installed'
/usr/local/Library/Homebrew/cmd/doctor.rb:875:in `check_missing_deps'
/usr/local/Library/Homebrew/cmd/doctor.rb:1095:in `send'
/usr/local/Library/Homebrew/cmd/doctor.rb:1095:in `doctor'
/usr/local/Library/Homebrew/cmd/doctor.rb:1094:in `each'
/usr/local/Library/Homebrew/cmd/doctor.rb:1094:in `doctor'
/usr/local/Library/brew.rb:95:in `send'
/usr/local/Library/brew.rb:95