bug#56592: 29.0.50; Moving between nnselect groups sometimes fails to save marks

[Sean Whitton <spwhitton@spwhitton.name>]

Hello,

You need a notmuch setup to reproduce this, though maybe other
gnus-search backends would show it too.  Create two nnselect groups
where the query for the second includes some of the messages in the
first group.  This is what I am using:

    first group, nnselect:Weekday, has query
      "to:spwhitton@spwhitton.name or to:spwhitton@arizona.edu"

    second group, nnselect:Weekend, has query
      "to:spwhitton@spwhitton.name".

So, messages addressed to spwhitton@spwhitton.name appear in both.
Ensure there are unread messages addressed to spwhitton@spwhitton.name.
Enter the first group, mark one of those messages addressed to
spwhitton@spwhitton.name as read.  Go to the last message, use 'n n' to
move to the next unread group.

The message that was marked as read reappears, unread, in the second
group.  If you quit to the group buffer and reenter the first group,
it's unread again there.

By contrast, if you mark the message as read in the first group and then
type C-x C-s, and only then do 'n n' on the last message, the marks are
properly saved and the message does not appear unread in the second
group.

I have nnselect-rescan t for the groups, in case that is relevant.

-- 
Sean Whitton