Don't output Ruby warnings

We don't want bug reports about this crap, even though the user REALLY should listen to the warning message. What actually happens is they blame us instead.

This kind of warning in particular:

warning: Insecure world writable dir /usr/local/bin in PATH

Library/Homebrew/formula_installer.rb

@@ -196,6 +196,7 @@ class FormulaInstaller
         read.close
         exec '/usr/bin/nice',
              '/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby',
+             '-W0',
              '-I', Pathname.new(__FILE__).dirname,
              '-rbuild',
              '--',

bin/brew

-#!/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
+#!/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby -W0
 # -*- coding: utf-8 -*-
 
 HOMEBREW_BREW_FILE = ENV['HOMEBREW_BREW_FILE'] = File.expand_path(__FILE__)