module Bundler::BuildMetadata

def self.git_commit_sha

The SHA for the git commit the bundler gem was built from. 
def self.git_commit_sha
  return @git_commit_sha if instance_variable_defined? :@git_commit_sha
  # If Bundler has been installed without its .git directory and without a
  # commit instance variable then we can't determine its commits SHA.
  git_dir = File.join(File.expand_path("../../../..", __FILE__), ".git")
  if File.directory?(git_dir)
    return @git_commit_sha = Dir.chdir(git_dir) { `git rev-parse --short HEAD`.strip.freeze }
  end
  @git_commit_sha ||= "unknown"
end