[NEW PORT] devel/py-flaky

Plugin for nose or pytest that automatically reruns flaky tests

Ideally, tests reliably pass or fail, but sometimes test fixtures must rely
on components that aren't 100% reliable.

With flaky, instead of removing those tests or marking them to skip, they
can be automatically retried.

WWW: https://github.com/box/flaky

Reviewed by: koobs
Approved by: koobs
Differential Revision: https://reviews.freebsd.org/D21132