Generated by `pyupgrade --py3-plus --keep-percent-format` on all our
Python code except `zthumbor` and `zulip-ec2-configure-interfaces`,
followed by manual indentation fixes.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
If a request fails the tool sleeps for some time before making
further requests. The sleep time is a random number between
0 and 2^failures capped at 64 seconds. More details about the
algorithm can be found at https://chat.zulip.org/#narrow/stream/
92-learning/topic/exponential.20backoff.20--.20with.20jitter
