Name sc-build number with git's HEAD

gistfile1.rb

module CT
  module Git
    def self.sha(repo)
      result = `cd "#{repo}" && git log -1 --format=%H`.strip
      return result =~ /^[0-9a-f]{40}$/ ? result : nil
    end
  end
end

config :sproutcore, :build_number => CT::Git::sha('frameworks/sproutcore')