brew --config

HOMEBREW_VERSION: 0.9.4
ORIGIN: https://github.com/mxcl/homebrew.git
HEAD: 867f60b7ab08722763312c91a2400f93d3248e0b
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CELLAR: /usr/local/Cellar
CPU: dual-core 64-bit penryn
OS X: 10.8.4-x86_64
Xcode: 4.6.3
CLT: 4.6.0.0.1.1365549073
LLVM-GCC: build 2336
Clang: 4.2 build 425
X11: N/A
System Ruby: 1.8.7-358
Perl: /usr/bin/perl
Python: /usr/bin/python
Ruby: /usr/bin/ruby => /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby

brew doctor

Warning: Your compilers are different from the standard versions for your Xcode.
If you have Xcode 4.3 or newer, you should install the Command Line Tools for
Xcode from within Xcode's Download preferences.
Otherwise, you should reinstall Xcode.

HOMEBREW_MAKE_JOBS=1 VERBOSE=1 brew install io 2>&1

Error: comparison of Fixnum with String failed
Please report this bug:
    https://github.com/mxcl/homebrew/wiki/troubleshooting
/usr/local/Library/Homebrew/formula.rb:215:in `>='
/usr/local/Library/Homebrew/formula.rb:215:in `fails_with?'
/usr/local/Library/Homebrew/requirements/python_dependency.rb:204:in `any?'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/set.rb:195:in `each'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/set.rb:195:in `each_key'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/set.rb:195:in `each'
/usr/local/Library/Homebrew/formula.rb:214:in `any?'
/usr/local/Library/Homebrew/formula.rb:214:in `fails_with?'
/usr/local/Library/Homebrew/build.rb:141:in `install'
/usr/local/Library/Homebrew/build.rb:43:in `main'
/usr/local/Library/Homebrew/build.rb:12
/usr/local/Library/Formula/io.rb:41