Seen again recently on Travis CI:
https://travis-ci.org/wikimedia/mediawiki/jobs/433020634
1) MediaWiki\Tests\Storage\DerivedPageDataUpdaterTest::testGetPreparedEditAfterPrepareUpdate Failed asserting that two strings are identical. --- Expected Actual @@ @@ -'20180925161827' '20180925161826' /home/travis/build/wikimedia/mediawiki/tests/phpunit/includes/Storage/DerivedPageDataUpdaterTest.php:487
Looks like there's some non-explicit assumption in this test based on a variable timestamp.
Recent changes: