bug#70948: 29.3; cperl mode hangs on comments like "#___"

[Eli Zaretskii]

> From: Patrick Goldmann <patrick.goldmann@gmail.com>
> Date: Tue, 14 May 2024 18:35:48 +0200
> 
> While trying to open files (with cperl-mode, perl-mode works) containing 
> comments of this sort, emacs hangs.
> 
> This also occurs when editing a new file in cperl-mode and trying to input a 
> comment like that.
> 
> Verified it's not my ~/.emacs.d/ by running emacs -Q
> 
> I guess cperl-mode is mistaking this for something like __PACKAGE__ etc

Can you please show an example of such a file?  I tried to reproduce,
perhaps too naïvely, and failed to see Emacs hang.

Thanks.