lava_wait_jobs.py: fetch_artifacts: Retry in case of IO errors

Retry on the level of a single job, to avoid refetching all jobs again
while overloading LAVA.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I8fb90159192d26691c0a68643cbf7e598133331f
1 file changed