PYTHON-1654 Ignore $clusterTime in test_command assertion

(cherry picked from commit d43ca11)

test/test_database.py

@@ -434,13 +434,8 @@ def test_command(self):
         first = db.command("buildinfo")
         second = db.command({"buildinfo": 1})
         third = db.command("buildinfo", 1)
-        # The logicalTime and operationTime fields were introduced in MongoDB
-        # 3.5. Their value can change from one command call to the next.
-        for doc in (first, second, third):
-            doc.pop("logicalTime", None)
-            doc.pop("operationTime", None)
-        self.assertEqual(first, second)
-        self.assertEqual(second, third)
+        self.assertEqualReply(first, second)
+        self.assertEqualReply(second, third)
 
     # We use 'aggregate' as our example command, since it's an easy way to
     # retrieve a BSON regex from a collection using a command. But until