According to the task schema, that parameter should not be null and defaults to
0. But current scheduler backend implementation expects a value nonetheless and
if it's null, that breaks the call.
Not necessarily for review, just to ensure it's fine jenkins wise.
This should fix [1]
[1]
https://jenkins.softwareheritage.org/job/DENV/job/tests/lastFailedBuild/artifact/swh-indexer.log