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

在交互式 CPython 3.13 会话中定义 class B 后，使用 inspect.getsource(B) 重现该问题。将返回的文本与类定义进行比较；当返回的是类源代码而不是无关的 REPL 内部信息时，即表示完成。