test_large_pool with _TestImportStar

[encukou]

The Debian buildbot sometimes runs out of memory (OSError: [Errno 12] Cannot allocate memory in fork()) around these multiprocessing tests:

• _TestImportStar (test.test_multiprocessing_forkserver.test_misc._TestImportStar.test_import), which imports all multiprocessing modules
• test_large_pool (test.test_multiprocessing_forkserver.test_misc.MiscTestCase.test_large_pool), which forks 200 processes

[encukou]

This was an issue in the VM.