bug#35613: Cursor returns to wrong article!

[積丹尼 Dan Jacobson]

I discovered a massive bug. A bug that could cause the user to lose mail.

In the *Summary* buffer use a few
 <down> [next-line]
until the cursor is upon call it, article A.
 <return> [gnus-summary-scroll-up]
 <down> [next-line] (once or more)
 <return> [gnus-summary-scroll-up]
 <tab> [gnus-summary-widget-forward]
 = [gnus-article-read-summary-keys]
Even though the ">" arrow at left and the underline are on a different article,
but the cursor now returns to Article A!!

Now if he hits e.g., the E key, he will mark the wrong article!
Or if he forwards it to his grandmother, she will die because he
forwarded the wrong article and she had a heart attack. See, gnus kills people!

Sure you will argue that that is a feature, however I used the same
 <return> [gnus-summary-scroll-up]
twice and for no good reason you remember the first one.

Gnus v5.13
GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.4)
 of 2019-02-03, modified by Debian