In updated patch the "xpickle" resource is tested before attempts to run Python executables. Also these checks are moved from decorator to the setUp() method. The result of have_python_version() now is memoized. Fixed running the test in unicode-disabled build. And added tests for installed Python 2.7. As far as older Python versions are rarely installed nowadays, this allows to check that the test is work at all (and that there is no significant regression against previous bugfix).