As discovered when investigating T200693 it turned out that apparently quibble job for Wikibase does not pull in Scribunto extension, which results in quite some tests not being run.
We might have missed the test failure that potentially quibble job could have spotted.
I cannot at least Scribunto listed in EXT_DEPENDENCIES in https://integration.wikimedia.org/ci/job/wmf-quibble-vendor-mysql-hhvm-docker/2192/parameters/. With quick look I failed a place in integration/config repo where I could add Scribunto there, thus the ticket.