This particular QUnit test failure has been causing builds to fail in MediaWiki core and other extensions.
```name=qunit
FAILED TESTS (1/1):
ve.ui.MWWikitextStringTransferHandler (Cite)
✖ convert
Error: Pending AJAX requests: 1 (active: 1)
```
* https://integration.wikimedia.org/ci/job/wmf-quibble-vendor-mysql-hhvm-docker/4785/console
* https://integration.wikimedia.org/ci/job/wmf-quibble-vendor-mysql-hhvm-docker/4788/console
I'm unsure as to what code initiates the faulty/untracked Ajax request, but it's likely either the above test itself or a test shortly before it.
The debug log from the above Jenkins builds shows the last HTTP fetch to be for a url `/null` which seems like a bug, but might be unrelated.
```
00:11:12.519 03 09 2018 18:46:49.694:DEBUG [middleware:source-files]: Requesting /null /
00:11:12.520 03 09 2018 18:46:49.695:DEBUG [middleware:source-files]: Fetching /null
00:11:12.521 03 09 2018 18:46:49.696:DEBUG [proxy]: proxying request - /null to 127.0.0.1:9412
```