Merge "releasetools: Track the change to BuildInfo." into oc-mr1-dev-plus-aosp

  if source_file is not None:

    cmd.extend(["--source_image", source_file])

  if OPTIONS.downgrade:

    max_timestamp = GetBuildProp("ro.build.date.utc", OPTIONS.source_info_dict)

    max_timestamp = source_info.GetBuildProp("ro.build.date.utc")

  else:

    max_timestamp = metadata["post-timestamp"]

  cmd.extend(["--max_timestamp", max_timestamp])