update log message in merge_default_config

Signed-off-by: Zhiyuan Chen <[email protected]>

chanfig/parser.py

@@ -320,11 +320,14 @@ def add_config_argument(self, key, value: Any | None = None, dtype: type | None
             return self.add_argument(name, type=dtype, help=help, dest=key)
 
     def merge_default_config(self, parsed, default_config: str, no_default_config_action: str = "raise") -> NestedDict:
-        message = f"default_config is set to {default_config}, but not found in args."
         if default_config in parsed:
             path = parsed[default_config]
-            warn(f"Config has 'default_config={path}' specified, its values will override values in Config")
+            warn(
+                f"{self.__class__.__name__} has 'default_config={path}' specified, "
+                "its values will override values in Config"
+            )
             return NestedDict.load(path).merge(parsed)
+        message = f"{self.__class__.__name__} has default_config set to {default_config}, but it is not found in args."
         if no_default_config_action == "ignore":
             pass
         elif no_default_config_action == "warn":