bug#37728: gnus-summary-isearch-article not worth the trouble

[積丹尼 Dan Jacobson]

s runs the command gnus-summary-isearch-article...

and is a total bummer, because once you have found the text, all you can
do is look at it. If you want to copy it, sorry: any exiting the search
flies you back to the *Summary* buffer.

That's why "s" is so weird. It would be better if it never existed in
the first place. The user already knows how to switch to the *Article*
buffer and do C-s there like any other buffer.

Sure you could pack gnus-summary-isearch-article with extra ways to stop
the search, but it would be just making more unnecessary mess.

Gnus v5.13
GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.11)
 of 2019-09-23, modified by Debian