MediaWikiTestCaseTrait::createHookContainer doesn't work in the mediawiki-quibble-composer-mysql-php72-docker test, which is blocking the merge of https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/581225/ ("Hooks::run() call site migration")
See https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/600091/ for a demonstration of the failure
1) MediaWiki\Tests\Rest\Handler\CreationHandlerTest::testHookContainer Error: Class 'Pimple\Psr11\ServiceLocator' not found /workspace/src/tests/phpunit/MediaWikiTestCaseTrait.php:73 /workspace/src/tests/phpunit/integration/includes/Rest/Handler/CreationHandlerTest.php:518 /workspace/src/tests/phpunit/MediaWikiIntegrationTestCase.php:437 /workspace/src/tests/phpunit/phpunit.php:75 /workspace/src/maintenance/doMaintenance.php:105 /workspace/src/tests/phpunit/phpunit.php:134
Does Pimple need to be added to core's composer.json?