kobo/xmlrpc.py: handle CannotSendRequest in retry_request_decorator()
kobo/xmlrpc.py: handle CannotSendRequest in retry_request_decorator()

It is usually a recoverable error, so it is not necessary to interrupt
the worker altogether.  In some cases, this even prevented the worker
from uploading the traceback back to the hub.

release-engineering/kobo,release-engineering/kobo,release-engineering/kobo,release-engineering/kobo