inspect.getsource returns irrelevant text when used in repl on a class defined in place

Bug report

Bug description:

Run interactive cpython 3.13 with following input.

>>> import inspect
>>> class B: pass
...
>>> inspect.getsource(B)
"# Important: don't add things to this module, as they will end up in the REPL's\n"

Instead of class code we get a piece of repl internals.

CPython versions tested on:

3.13

Operating systems tested on:

Windows

Linked PRs

• gh-126032

在互動式 CPython 3.13 工作階段中就地定義 class B 後，使用 inspect.getsource(B) 重現問題。將傳回的文字與類別定義進行比較；當傳回的是類別原始碼而不是無關的 REPL 內部資訊時，即表示完成。