`get_headers` caching should be cleaned on delete()

[cprov]

I understand the caching implemented on get_headers (https://github.com/dennisv/django-storage-swift/blob/master/swift/storage.py#L303) is useful for the reasons described in the code, however it causes a little bit of a pain the following scenario:

When one can't enable AUTO_OVERWRITE, trying to reusing the same filename will always fail, e.g:

if storage.exists(path):
    storage.delete(path)
storage.save(path)

save() calls get_available_name() which, because of the cached results, detects the path still exists and appends the disambiguating suffix. Implicitly adding the suffix is a bad behaviour, but having to clean the cache manually is even worse:

if storage.exists(path):
    storage.delete(path)
    storage.last_headers_name = None
storage.save(path, content)

Could it be done in https://github.com/dennisv/django-storage-swift/blob/master/swift/storage.py#L327 ?

[KostyaEsmukov]

Resetting last_headers_name in delete will definitely help in this particular use-case, but there're others where this cache should be invalidated as well, such as rmtree, _save, and (probably, though I'm not sure) makedirs.