class Gem::Commands::EnvironmentCommand

def git_path
  exts = ENV["PATHEXT"] ? ENV["PATHEXT"].split(";") : [""]
  ENV["PATH"].split(File::PATH_SEPARATOR).each do |path|
    exts.each do |ext|
      exe = File.join(path, "git#{ext}")
      return exe if File.executable?(exe) && !File.directory?(exe)
    end
  end
  nil
end