**Steps to reproduce**
* View this change https://gerrit.wikimedia.org/r/#/c/311463/ (it passed when it was merged but doing a recheck fails)
* See the failed test https://integration.wikimedia.org/ci/job/mediawiki-extensions-qunit-jessie/19388/console
**Actual results**
* It is failing with
16:56:04 18 12 2016 16:56:03.129:DEBUG [launcher]: Chrome (id 41038593) captured in 1.288 secs
16:56:04 18 12 2016 16:56:03.149:DEBUG [middleware:karma]: custom files null null
16:56:04 18 12 2016 16:56:03.149:DEBUG [middleware:karma]: Serving static request /context.html
16:56:04 18 12 2016 16:56:03.154:DEBUG [web-server]: serving: /home/jenkins/workspace/mediawiki-extensions-qunit-jessie/src/node_modules/karma/static/favicon.ico
16:56:04 18 12 2016 16:56:03.156:DEBUG [web-server]: serving: /home/jenkins/workspace/mediawiki-extensions-qunit-jessie/src/node_modules/karma/static/context.html
16:56:04 18 12 2016 16:56:03.169:DEBUG [middleware:source-files]: Requesting /base/node_modules/qunitjs/qunit/qunit.js?28e1c466df9848ed4d3a9fe432636b5a198b6c3e /
16:56:04 18 12 2016 16:56:03.169:DEBUG [middleware:source-files]: Fetching /home/jenkins/workspace/mediawiki-extensions-qunit-jessie/src/node_modules/qunitjs/qunit/qunit.js
16:56:04 18 12 2016 16:56:03.172:DEBUG [middleware:source-files]: Requesting /base/node_modules/karma-qunit/lib/adapter.js?2cc5e3594a3b8ae53e8218929324788866ad223b /
16:56:04 18 12 2016 16:56:03.173:DEBUG [middleware:source-files]: Fetching /home/jenkins/workspace/mediawiki-extensions-qunit-jessie/src/node_modules/karma-qunit/lib/adapter.js
16:56:04 18 12 2016 16:56:03.175:DEBUG [web-server]: serving (cached): /home/jenkins/workspace/mediawiki-extensions-qunit-jessie/src/node_modules/qunitjs/qunit/qunit.js
16:56:04 18 12 2016 16:56:03.178:DEBUG [web-server]: serving (cached): /home/jenkins/workspace/mediawiki-extensions-qunit-jessie/src/node_modules/karma-qunit/lib/adapter.js
16:56:04 18 12 2016 16:56:03.180:DEBUG [web-server]: serving: /home/jenkins/workspace/mediawiki-extensions-qunit-jessie/src/node_modules/karma/static/context.js
16:56:07 Chrome 55.0.2883 (Linux 0.0.0) ERROR
16:56:07 Script error.
16:56:07
16:56:07
16:56:07 18 12 2016 16:56:06.141:DEBUG [karma]: Run complete, exiting.
16:56:07 18 12 2016 16:56:06.142:DEBUG [launcher]: Disconnecting all browsers
16:56:07 18 12 2016 16:56:06.251:DEBUG [launcher]: Process Chrome exited with code 0
16:56:07 18 12 2016 16:56:06.251:DEBUG [temp-dir]: Cleaning temp dir /home/jenkins/tmpfs/jenkins-0/karma-41038593
16:56:07 18 12 2016 16:56:06.292:DEBUG [launcher]: Finished all browsers
16:56:07 Warning: Task "karma:main" failed. Use --force to continue.
Note: Strange the last merged patch https://gerrit.wikimedia.org/r/#/c/324959/ passed but doing recheck's on other patches are failing.
Looking at the build history:
```
$ grep 'Script error' /srv/jenkins/builds/*qunit*/*/log|cut -d\/ -f5|uniq -c
3 mediawiki-core-qunit-jessie
70 mediawiki-extensions-qunit-jessie
```
`mediawiki-core-qunit-jessie` runs against mediawiki/core and has no dependencies beside `mediawiki/vendor`. The failing builds are:
|Time | Gerrit | Console | Chromium
|--|--|--|--
| Dec 12 16:05 UTC | [[ https://gerrit.wikimedia.org/r/#/c/325049/13 | 325049/13 ]] | [[ https://integration.wikimedia.org/ci/job/mediawiki-core-qunit-jessie/9842/console | 9842 ]] | Chrome 53.0.2785
| Dec 12 16:14:41 UTC | [[ https://gerrit.wikimedia.org/r/#/c/325049/14 | 325049/14]] | [[ https://integration.wikimedia.org/ci/job/mediawiki-core-qunit-jessie/9843/console | 9843 ]] | Chrome 53.0.2785
| Dec 16 21:47:08 UTC | [[ https://gerrit.wikimedia.org/r/#/c/325049/15 | 325049/15 ]] | [[ https://integration.wikimedia.org/ci/job/mediawiki-core-qunit-jessie/10154/console | 10154 ]] | Chrome 55.0.2883
Note that Gerrit change 325049 hasn't been merged. I have rebuild 9842 twice (in Jenkins UI with the Rebuild link in the web interface) and it failed with the same error. So it seems those patches manage to reproduce the issue at hand.
I have triggered the build against the `master` branch and it passed three times [[ https://integration.wikimedia.org/ci/job/mediawiki-core-qunit-jessie/10304/console | 10304 ]] [[ https://integration.wikimedia.org/ci/job/mediawiki-core-qunit-jessie/10305/console | 10305 ]] [[ https://integration.wikimedia.org/ci/job/mediawiki-core-qunit-jessie/10306/console | 10306 ]].