gh-145301: Fix double-free in hmac module initialization

Author: krylosov-aa

Lib/test/test_hashlib.py

@@ -68,7 +68,6 @@ def get_fips_mode():
 
 requires_sha3 = unittest.skipUnless(_sha3, 'requires _sha3')
 
-_testcapi = import_helper.import_module('_testcapi')
 
 def hexstr(s):
     assert isinstance(s, bytes), repr(s)
@@ -1205,12 +1204,10 @@ def test_readonly_types(self):
                         hash_type.value = False
 
     @unittest.skipUnless(HASH is not None, 'need _hashlib')
-    @unittest.skipUnless(hasattr(_testcapi, 'set_nomemory'),
-                         'need _testcapi.set_nomemory()')
     def test_hashlib_init_memory_error_no_df(self):
         """gh-145301 regression test."""
+        import_helper.import_module('_testcapi')
         code = textwrap.dedent("""
-            import sys
             import _testcapi
             _testcapi.set_nomemory(40, 41)
             try: