Test part: upb CopyFrom the default empty message should just clear instead of deep copy

from memory

fix https://github.com/protocolbuffers/protobuf/issues/13485

PiperOrigin-RevId: 559888172

protobuf_deps.bzl

@@ -150,6 +150,6 @@ def protobuf_deps():
         _github_archive(
             name = "upb",
             repo = "https://github.com/protocolbuffers/upb",
-            commit = "823a12e80934f9c8fb9178191d69f06a1bbfd604",
-            sha256 = "165f425714d32018a1a856b1935cfa24206878f8a469384808d2dce1d7c4003a",
+            commit = "57636ce03ac1e2aab3a362a61a6664981e21cda5",
+            sha256 = "75da534db927e165cb550d232c35e2dec4b5153b3b47989b250d75febbfc1710",
         )

python/google/protobuf/internal/message_test.py

@@ -422,6 +422,22 @@ class MessageTest(unittest.TestCase):
     empty.ParseFromString(populated.SerializeToString())
     self.assertEqual(str(empty), '')
 
+  def testCopyFromEmpty(self, message_module):
+    msg = message_module.NestedTestAllTypes()
+    test_msg = message_module.NestedTestAllTypes()
+    test_util.SetAllFields(test_msg.payload)
+    self.assertTrue(test_msg.HasField('payload'))
+    # Copy from empty message
+    test_msg.CopyFrom(msg)
+    self.assertEqual(0, len(test_msg.ListFields()))
+
+    test_util.SetAllFields(test_msg.payload)
+    self.assertTrue(test_msg.HasField('payload'))
+    # Copy from a non exist message
+    test_msg.CopyFrom(msg.child)
+    self.assertFalse(test_msg.HasField('payload'))
+    self.assertEqual(0, len(test_msg.ListFields()))
+
   def testAppendRepeatedCompositeField(self, message_module):
     msg = message_module.TestAllTypes()
     msg.repeated_nested_message.append(