When Marionette is running tests in the target application, and you issue ctrl-c in the terminal, Marionette quits but does not close the application it has started. Marionette should be made failure-proof so that the application under test is always closed whatever happens to Marionette. Otherwise instances of the application will continue to exist, and can badly interact with following tests.

is this in general or e10s specific?

I don't have underlined tab names when running the tests from the firefox-greenlight repository. So the browser is not running in e10s mode, and this applies in general.

/r/1147 - Bug 1104742 - Marionette runner should cleanup marionette objects when gc'ed, r=AutomatedTester Pull down this commit: hg pull review -r 8a869167794d3bb439d167f4d29ceb8c820a5ebf

https://reviewboard.mozilla.org/r/1145/#review667 Ship It!