<https://travis-ci.org/wikimedia/mediawiki/jobs/392321537>
<https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/416465/> / T174024
The builds were passing before this commit and started failing after it.
```counterexample
There was 1 failure:
1) MediaWiki\Tests\Storage\McrRevisionStoreDbTest::testInsertRevisionOn_successes with data set "Multi-slot revision insertion" (array(array(WikitextContent Object (...), TextContent Object (...)), true, CommentStoreComment Object (...), '20171117010101', true))
Failed asserting that two arrays are equal.
--- Expected
+++ Actual
@@ @@
Array (
- 0 => 'main'
- 1 => 'aux'
+ 0 => 'aux'
+ 1 => 'main'
/home/travis/build/wikimedia/mediawiki/tests/phpunit/includes/Storage/RevisionStoreDbTestBase.php:277
/home/travis/build/wikimedia/mediawiki/tests/phpunit/includes/Storage/RevisionStoreDbTestBase.php:415
```