As observed in [[https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/Math/+/565622/|r565622]], tests currently fail on Math because of:
> PHP Fatal error: Declaration of MathMLRdfBuilder::addValue(Wikimedia\Purtle\RdfWriter $writer, $propertyValueNamespace, $propertyValueLName, $dataType, Wikibase\DataModel\Snak\PropertyValueSnak $snak) must be compatible with Wikibase\Rdf\ValueSnakRdfBuilder::addValue(Wikimedia\Purtle\RdfWriter $writer, $propertyValueNamespace, $propertyValueLName, $dataType, $snakNamespace, Wikibase\DataModel\Snak\PropertyValueSnak $snak) in /workspace/src/extensions/Math/src/MathMLRdfBuilder.php on line 7
This failure is clearly not spurious, and was caused by [[https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/Wikibase/+/533202/|r533202]] for Wikibase. I'm unsure what the fix is [1], but either way, this needs to be fixed before the next train.
[1] - Maybe just adding that extra parameter would suffice, but I'm no confident enough with Wikibase to know if that's true.