Redundant thread titles when using dummy roots

[Kévin Le Gouguec]

Hello,

I have configured Gnus to gather loose threads under a dummy root
article.  I have "%S" set in gnus-summary-dummy-line-format, and %s in
gnus-summary-line-format: my intent is to have the thread subject show
up only once, on the dummy root.

Sometimes this works:

                     ┌◈                          bug#40337: 28.0.50; Enable 
case-fold-search in hi-lock
    02:08            ├► Juri Linkov
    05:33            ╰► Stefan Monnier

And sometimes it doesn't:

                     ┌◈                          Re: Emacs's set-frame-size can 
not work well with gnome-shell?
    10:32            ├► martin rudalics          Re: Emacs's set-frame-size can 
not work well with gnome-shell?
    16:04            │╰► Eli Zaretskii
    10:33            ├► martin rudalics
    15:19            │╰► Dmitry Gutov
    10:33            ╰► martin rudalics

I poked at lisp/gnus/gnus-sum.el and reported this as bug#40520, where I
suggested the following patch:

0001-Simplify-dummy-root-subject-before-comparing-it-to-t.patch
Description: Text Data

As I said in the report, unless I'm mistaken, gnus-tmp-prev-subject's
sole purpose is to be compared with simp-subject.  Since the latter goes
through gnus-simplify-subject-fully, it seems right that the former
would go through it too…

So far the report has not received much attention.  I figure it could be
a good idea to ask this list for feedback: is this an issue someone else
has run into?  Could it be something from my configuration (which I've
posted as a footnote in the bug report)?

Also, I imagine that this list is one of the best places to find people
who can answer the question I asked in my bug report's second footnote:
how would one go about writing an ERT test case for this?


Thank you for your time.