Running tests in parallel with processes wasn't failing fast when the
option was enabled. The problem was that even when the reporter raised
the `Interrupt` exception, the queue was not emptied, so workers keep
processing jobs as if nothing happened.

This patch basically intercepts the `Interrupt` exception that may
come from the reporter, and tells the server to clear the jobs queue,
so that it can continue the shutdown process as usual. The exception
must then continue its journey so that the backtrace is displayed.