Re: bug#74934: 30.0.92; Unexpected behavior by which-function-mode in erc-mode buffers

> Cc: [email protected], [email protected]
> From: "J.P." <[email protected]>
> Date: Tue, 17 Dec 2024 18:24:02 -0800
> 
> > steps to reproduce:
> > emacs --no-init
> > M-x erc
> > ;; join some channel.
> > M-x which-function-mode
> >
> > Current behavior:
> > In erc buffers, which-function-mode displays either "[n/a]" or a string based on
> > the chat history in the mode line.
> 
> FTR, I'm able to reproduce it.
> 
> > Expected behavior:
> > which-function-mode shouldn’t be adding any string to mode line in erc buffers
> 
> The first of the attached patches should hopefully address the issue.

Is this for the release branch?  That is, is this a recent regression?

And if so, what is the second patch for?

Thanks.