Here's another retry abstraction that in some ways is more general (decide whether to keep trying some other way, or sleep a bit before the next try, etc.): https://github.com/darius/sketchbook/blob/master/misc/retryi...

A couple things look wrong in the OP's last snippet: shouldn't

    ignore_small = ignore(ImageTooSmall)

be

    ignore_small = lambda call: ignore(call, ImageTooSmall)

and similarly for the definition of http_retry?