Issue28082, for 3.6.0b1, modified the re module to use enum.IntFlag.  As described in Issue19325, on interpreter startup site.py imports sysconfig which, on OS X, imports _osx_support which imports, among other things, re.  Now that re imports enum, a number of collections modules are also imported at startup on OS X which can have a negative performance impact.  test_startup_imports of test_site was designed to catch situations like this ... and does.

For 3.6.0b1, I'm going to skip the failing part of the test on OS X only.  For 3.6.0b2, I'll plan to revive languishing Issue19325 to at least try to remove the usage of re and then re-enable the skipped test.