Set entity field as expected

Fixes this failing test

1) Wikibase\Test\EntityCacheUpdaterTest::testHandleChange
MWException: The provided Change does not contain full entity data!

/home/j/www/phase3/extensions/Wikibase/client/includes/EntityCacheUpdater.php:50
/home/j/www/phase3/extensions/Wikibase/client/tests/phpunit/includes/EntityCacheUpdaterTest.php:71
/home/j/www/phase3/tests/phpunit/MediaWikiTestCase.php:116
/home/j/www/phase3/tests/phpunit/MediaWikiPHPUnitCommand.php:63
/home/j/www/phase3/tests/phpunit/MediaWikiPHPUnitCommand.php:47

Change-Id: Ic498d01aac986f060ffeaa95bc57813dc974d5cd
Merge "Set entity field as expected"