run_tests hangs on Linux

[quisquous]

./run_tests
testAppSideUncaughtErrorObject (chromeapp_unittest.AppTest) ...

And the browser window opens and just sits there. This is on my corp Linux desktop. If I close the browser window, the process repeats:

Browser closed without notifying us. Exiting...
ok
testAppThatPrints (chromeapp_unittest.AppTest) ...

...and it sits there forever.