test_zlib failure is on zlib.crc32(mmap.mmap(...)) with a mapping bigger than 4 GB:
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# Issue #10276 - check that inputs >=4GB are handled correctly.
class ChecksumBigBufferTestCase(unittest.TestCase):

    def setUp(self):
        with open(support.TESTFN, "wb+") as f:
            f.seek(_4G)
            f.write(b"asdf")
        with open(support.TESTFN, "rb") as f:
            self.mapping = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)

    def tearDown(self):
        self.mapping.close()
        support.unlink(support.TESTFN)

    @unittest.skipUnless(mmap, "mmap() is not available.")
    @unittest.skipUnless(sys.maxsize > _4G, "Can't run on a 32-bit system.")
    @unittest.skipUnless(support.is_resource_enabled("largefile"),
                         "May use lots of disk space.")
    def test_big_buffer(self):
        self.assertEqual(zlib.crc32(self.mapping), 3058686908) <~~~ HERE
        self.assertEqual(zlib.adler32(self.mapping), 82837919)
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It looks to be related to #11277 (and #10276).