You can only reproduce this with an old cache because the librarian sends a Cache-Control header when it serves a file:
cache-control: public,max-age=604800
That tells httplib2 it's okay to keep the file cached for a week. There's a request httplib2 could make that would trigger the problem, but httplib2 won't make that request until a week after you first get the file. During that week it will retrieve the file's representation from the cache.
I can trigger this error reliably by hacking the max-age header in the cache. Working on a fix now.
You can only reproduce this with an old cache because the librarian sends a Cache-Control header when it serves a file:
cache-control: public, max-age= 604800
That tells httplib2 it's okay to keep the file cached for a week. There's a request httplib2 could make that would trigger the problem, but httplib2 won't make that request until a week after you first get the file. During that week it will retrieve the file's representation from the cache.
I can trigger this error reliably by hacking the max-age header in the cache. Working on a fix now.