Please note that tests/runtestfedabipkdiff.py is relatively fast for
the moment. But when it contains much more tests and start becoming
slow, then we'll need to change the code to run several comparisons in
parallel, just like we do today in tests/test-diff-filter.cc. At that
point, I believe I'll just re-write this in C++, just like
tests/test-diff-filter.cc because that will allow us to have true
concurrent code based on the abigail:workers API. For now, I am
keeping this in Python also because I think that keeps Chenxiong happy
;-)