fix test runner and pyximport in Py 2.7.9 and 3.4+: setuptools replaces "distutils.dist.Distribution" *after* we import it, which then breaks the input validation in "distutils.cmd"

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extra : transplant_source : %3A%84%AC%02E%17%D8%EE%E64Mpv%25%A3%8E%8B%E5%CA%19