As for 3.x, underscored test does not run, and when remove the underscore it runs, but produce a warning (you should run regrtests with -vv to see detailed warnings):

$ ./python -m test.regrtest -vv -m '*no_import_lock_contention*' test_multiprocessing_spawn
...
Warning -- threading._dangling was modified by test_multiprocessing_spawn
  Before: <_weakrefset.WeakSet object at 0xb6a960ac>
  After:  <_weakrefset.WeakSet object at 0xb6c4cc0c> 
1 test altered the execution environment:
    test_multiprocessing_spawn