https://integration.wikimedia.org/ci/job/wmf-quibble-core-vendor-mysql-hhvm-docker/6915/console and https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/479493/
```
17:27:07 1) McsContentProviderTest::testGetHtmlWithNoResponse
17:27:07 Undefined index: 1
17:27:07
17:27:07 /workspace/src/includes/http/MWHttpRequest.php:424
17:27:07 /workspace/src/includes/http/CurlHttpRequest.php:138
17:27:07 /workspace/src/extensions/MobileFrontend/includes/content-providers/McsContentProvider.php:61
17:27:07 /workspace/src/extensions/MobileFrontend/includes/content-providers/McsContentProvider.php:81
17:27:07 /workspace/src/extensions/MobileFrontend/tests/phpunit/content-providers/McsContentProviderTest.php:112
17:27:07 /workspace/src/tests/phpunit/MediaWikiTestCase.php:424
17:27:07 /workspace/src/maintenance/doMaintenance.php:94
```