Seen frequently on MobileFrontend e.g. https://integration.wikimedia.org/ci/job/mediawiki-extensions-qunit-jessie/56808/console
afterEach failed on Create & destroy: Pending AJAX requests: 0 (active: 1) 17:09:37 Error: Pending AJAX requests: 0 (active: 1)
Sounds like this qunit test may be firing an ajax request?