gh-126483: disable warnings filters mutation in concurrent test (GH-132694)

The `test_ssl_in_multiple_threads` test failed because `test_check_hostname_idn()`
modified the global warnings filters via `warnings_helper.check_no_resource_warning()`.
Only check for warnings when the context aware warnings feature is enabled, which makes
the warnings filter context-local and thread-safe.

Author: graingert

Lib/test/test_ssl.py

@@ -31,6 +31,7 @@
 import platform
 import sysconfig
 import functools
+from contextlib import nullcontext
 try:
     import ctypes
 except ImportError:
@@ -2843,6 +2844,7 @@ def test_ssl_in_multiple_threads(self):
         # See GH-124984: OpenSSL is not thread safe.
         threads = []
 
+        warnings_filters = sys.flags.context_aware_warnings
         global USE_SAME_TEST_CONTEXT
         USE_SAME_TEST_CONTEXT = True
         try:
@@ -2851,7 +2853,10 @@ def test_ssl_in_multiple_threads(self):
                 self.test_alpn_protocols,
                 self.test_getpeercert,
                 self.test_crl_check,
-                self.test_check_hostname_idn,
+                functools.partial(
+                    self.test_check_hostname_idn,
+                    warnings_filters=warnings_filters,
+                ),
                 self.test_wrong_cert_tls12,
                 self.test_wrong_cert_tls13,
             ):
@@ -3097,7 +3102,7 @@ def test_dual_rsa_ecc(self):
                 cipher = s.cipher()[0].split('-')
                 self.assertTrue(cipher[:2], ('ECDHE', 'ECDSA'))
 
-    def test_check_hostname_idn(self):
+    def test_check_hostname_idn(self, warnings_filters=True):
         if support.verbose:
             sys.stdout.write("\n")
 
@@ -3152,16 +3157,30 @@ def test_check_hostname_idn(self):
                                      server_hostname="python.example.org") as s:
                 with self.assertRaises(ssl.CertificateError):
                     s.connect((HOST, server.port))
-        with ThreadedEchoServer(context=server_context, chatty=True) as server:
-            with warnings_helper.check_no_resource_warning(self):
-                with self.assertRaises(UnicodeError):
-                    context.wrap_socket(socket.socket(),
-                            server_hostname='.pythontest.net')
-        with ThreadedEchoServer(context=server_context, chatty=True) as server:
-            with warnings_helper.check_no_resource_warning(self):
-                with self.assertRaises(UnicodeDecodeError):
-                    context.wrap_socket(socket.socket(),
-                            server_hostname=b'k\xf6nig.idn.pythontest.net')
+        with (
+            ThreadedEchoServer(context=server_context, chatty=True) as server,
+            (
+                warnings_helper.check_no_resource_warning(self)
+                if warnings_filters
+                else nullcontext()
+            ),
+            self.assertRaises(UnicodeError),
+        ):
+            context.wrap_socket(socket.socket(), server_hostname='.pythontest.net')
+
+        with (
+            ThreadedEchoServer(context=server_context, chatty=True) as server,
+            (
+                warnings_helper.check_no_resource_warning(self)
+                if warnings_filters
+                else nullcontext()
+            ),
+            self.assertRaises(UnicodeDecodeError),
+        ):
+            context.wrap_socket(
+                socket.socket(),
+                server_hostname=b'k\xf6nig.idn.pythontest.net',
+            )
 
     def test_wrong_cert_tls12(self):
         """Connecting when the server rejects the client's certificate