bug#42428: 28.0.50; Gnus will sometimes continue loading articles from previous group

[Lars Ingebrigtsen]

To reproduce:

1) Enter an NNTP group with a lot of articles.
2) Select the first article.  gnus-async will then start loading more
   articles.
3) Hit `c' or the like to go to the next group.
4) Select the first article.  gnus-async will start loading more
   articles.

Here's the bug:

5) Select the second article.  This will then show random article
   portions from the async in 2).

So the preceding async isn't cancelled, or is cancelled (and then
cleaned up?) the wrong way, leaving data in the server buffer that is
then interpreted as coming from the most recent gnus-async call.


In GNU Emacs 28.0.50 (build 8, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo 
version 1.16.0)
 of 2020-07-19 built on xo
Repository revision: 17f646128f04e9e8590f0371026a14d516f21c63
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Debian GNU/Linux bullseye/sid


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no