[kovidgoyal]

The robust way to do it would be something like:

base = iterator.base
csizes = {os.path.abspath(os.path.join(base, ci.filename)): ci.compress_size for ci in zf.infolist()}

for path in iterator.spine:
   sz = csizes.get(os.path.abspath(path))
   if sz is not None:
      ...