def rev_module_status(git_session, rev, local_path)
    mod_stat = nil
    if git_session.execute("git ls-tree -r --name-only #{rev}").split("\n").include?(File.join(local_path, ".riminfo"))
      git_session.within_exported_rev(rev, [local_path]) do |d|
        mod_stat = build_module_status(d, File.join(d, local_path))
      end
    end
    mod_stat
  end
def rev_module_status(git_session, rev, local_path)
    mod_stat = nil
    if git_session.execute("git ls-tree -r --name-only #{rev}").split("\n").include?(File.join(local_path, ".riminfo"))
      git_session.within_exported_rev(rev, [local_path]) do |d|
        mod_stat = build_module_status(d, File.join(d, local_path))
      end
    end
    mod_stat
  end
status object for a single module at +local_path+ in revision +rev+
 returns nil if there is no such module in this revision