We are still trying to get incomplete subunit files into our logs. This
is now failing because we assumed a single dict with a files entry to
iterate over but in reality we get a list of dicts with files entries to
iterate over. In order to iterate over this content we use
with_subelements to iterate over and copy the found files.
Change-Id: I160ac5caeec6fd7f5a35e805b7d4811b20405d14
4ab37d798a