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

filectx: remove dependencies on filerev Removing dependencies on filectx.filerev() makes it easier to create a filelog implementation that doesn't have rev numbers.

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)