Attempting to run any browser test locally fails. Error reported is "a is undefined". This seems to be a jquery issue. Googling for it suggests that it could affect actual users and not only automated tests. Full stack trace is:
a is undefined (Selenium::WebDriver::Error::JavascriptError)
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:26:in `F'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:39:in `Eb'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:50:in `T'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:60:in `Db'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:61:in `dc'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:61:in `anonymous/</<'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:14:in `anonymous/<'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit line 68 > Function:14:in `anonymous'
[remote server] http://en.wikipedia.beta.wmflabs.org/wiki/Bullets_VisualEditor_Test?vehidebetadialog=true&veaction=edit:68:in `handleEvaluateEvent'