More gracefully handle TimeoutException in test

Sometimes although the test_killed_worker_recover test passes, the
cleanup of a forked child takes too long and a TimeoutException
occurs. This patch better handles the TimeoutException and
ensures the child process is killed.

Fixes bug #1128574

Change-Id: I39ea2fbb6c9cb95ad10b68bfa216686467951a93
Merge "More gracefully handle TimeoutException in test"