KeyError: 'last-modified'

[wastemaster]

>>> fix_site_offer(135406)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/aggregator/aggregator/src/apps/images/utils.py", line 218, in fix_site_offer
    if not default_storage.exists('%s' % image.image):
  File "/home/aggregator/aggregator/.env/local/lib/python2.7/site-packages/django_selectel_storage/storage.py", line 89, in exists
    self.container.info(self._name(name))
  File "/home/aggregator/aggregator/.env/local/lib/python2.7/site-packages/selectel/storage.py", line 213, in method
    return fn(self.name, *args, **kwargs)
  File "/home/aggregator/aggregator/.env/local/lib/python2.7/site-packages/selectel/storage.py", line 13, in wrapper
    return fn(*args, **kwargs)
  File "/home/aggregator/aggregator/.env/local/lib/python2.7/site-packages/selectel/storage.py", line 162, in info
    dt = datetime.strptime(r.headers["Last-Modified"],
  File "/home/aggregator/aggregator/.env/local/lib/python2.7/site-packages/requests/structures.py", line 54, in __getitem__
    return self._store[key.lower()][1]
KeyError: 'last-modified'