avoid rerunning test in refleak hunting mode.

Author: gpshead

Lib/test/test_hashlib_fips.py

@@ -12,8 +12,12 @@
 
 
 class HashLibFIPSTestCase(unittest.TestCase):
+    _executions = 0  # prevent re-running on in refleak hunting mode, etc.
+
     @classmethod
     def setUpClass(cls):
+        if cls._executions > 0:
+            raise unittest.SkipTest("Cannot run this test within the same Python process.")
         if sys.modules.get("_hashlib") or sys.modules.get("_ssl"):
             raise AssertionError("_hashlib or _ssl already imported, too late to change OPENSSL_CONF.")
         # This openssl.cnf mocks FIPS mode without any digest
@@ -43,6 +47,7 @@ def tearDownClass(cls):
             os.environ["OPENSSL_CONF"] = OPENSSL_CONF_BACKUP
         else:
             os.environ.pop("OPENSSL_CONF", None)
+        cls._executions += 1
 
     def test_algorithms_available(self):
         import hashlib