hg: move return statement after finally block
return is always run after finally block. Now we have same functionality,
but clearer readability.
run-tests: call Threads constructor with keyword arguments
This is suggested in the python documentation
(on http://docs.python.org/2/library/threading.html#thread-objects)
run-tests: ignoring tests works again
running with --retest did not work anymore because runone still returned None
for this case. But this is not allowed since
6a127fa5de23.