hang when opening a rss-folder

Hi.

I am helping to debug a very old problem with wanderlust. There is a
patch on emacs master that helps.
see:
--8<---------------cut here---------------start------------->8---
https://lists.nongnu.org/archive/html/emacs-devel/2018-03/msg00001.html
--8<---------------cut here---------------end--------------->8---


I want to encourage You guys to try to get the hang and give me better
ideas how to reproduce it quickly or solving it (with the patch seems to
be solved on GNUS).

this is my reduced .folder file
--8<---------------cut here---------------start------------->8---
#
# Folder definition file
# This file is generated automatically by Wanderlust/2.15.9 (Almost Unreal).
#
# If you edit this file by hand, be sure that comment lines
# will be washed out by wl-fldmgr.
#

news{
        gwene {
        /last:1000/[email protected] "hnews"
        }
        gmane {
        /last:2000/[email protected] "emacs-devel"
        }
}

# petname definition (access group, folder in access group)

# end of file.
--8<---------------cut here---------------end--------------->8---

Adapt the above file to your own .folder file.

The hang occurs when opening the hnews or emacs-devel rss-folder. When
the hangs happens needs to be cancelled with (C-g).

At this moment. I am testing this with emacs-26 and emacs-27 (master
with the patch).

AR