run-tests: sort missing files first instead of raising an error sort first for early telling typos in test names [ original upstream message ]

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) [ original upstream message ]

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. [ original upstream message ]