In Emacs 27.2, list-matching-lines doesn't seem to respect case-fold-search

[MBR <mbr@arlsoft.com>]

A year or two ago I replaced my old MacBook with a new one, so I had to 
reinstall Emacs.  I'd been running Emacs 24.3.1 on the old laptop.  The 
latest stable version at the time I put the new one into service was 
Emacs 27.2, so I installed that on my new computer.  Ever since then, 
several bits of basic Emacs functionality that I regularly depend on 
have changed or stopped working properly, or are now exhibiting 
undesired behavior.  (E.G. toggle-read-only-mode stopped working, and I 
only just discovered that that's because it was renamed to 
read-only-mode. I really don't understand why toggle-read-only-mode 
couldn't have been retained as an alias for read-only-mode, just like 
delete-non-matching-lines was turned into an alias when that function 
was renamed to keep-matching-lines.  But that's not the question I'm 
seeking an answer to with this post.)

The really annoying change that I'm asking about today has to do with 
the variable case-fold-search and the function list-matching-lines. In 
all previous versions of Emacs, going back to at least the early '90s, 
setting case-fold-search to either tor nil affected the case sensitivity 
of all the search functionality I regularly use, which includes:

          * isearch-forward(bound to C-s),
          * isearch-forward-regexp(bound to M-C-s),
          * query-replace(bound to M-%),
          * query-replace-regexp,
          * list-matching-lines,
          * delete-matching-lines, and
          * delete-non-matching-lines

But now, setting case-fold-searchdoesn't affect the case sensitivity of 
list-matching-lines, even though it still affects all the other search 
functions I listed above.

Does anyone here have any idea why list-matching-lines no longer does a 
case-insensitive search when case-fold-searchis set to t?

        Mark Rosenthal
        mbr@arlsoft.com <mailto:mbr@arlsoft.com>