bug#35443: 27.0.50; Gnus (nnimap) shows "ghost" messages in summary buffer

[Ulrich Mueller]

>>>>> On Sat, 27 Apr 2019, Eric Abrahamsen wrote:

> Huh. Can you show us the value of gnus-newsgroup-data and
> gnus-newsgroup-headers in this group?

See below, for the current group, whose summary buffer shows your
article and a dummy article.

> Does the dummy article always show up?

It always shows up when new articles have been fetched. It doesn't
show up when entering a group that doesn't have new mail (i.e., if a
group previously had a dummy article, it will be gone when reentering
that group).

> Only in this group?

All groups for that particular IMAP server. 

> Is this a newly-added IMAP server, and did it display this problem
> right from the beginning?

AFAICS, the problem appeared after dovecot on the server side was
upgraded from version 2.2.34 to 2.3.5.1. But I see it only with Gnus.
I don't have any issues with Mozilla Thunderbird (on GNU/Linux) nor with
K-9 Mail (on Android/Linux).

----------------------------------------------------------------------
gnus-newsgroup-data is a variable defined in ‘gnus-sum.el’.
Its value is shown below.

Documentation:
Not documented as a variable.

Value:
((32415 82 2
        [32415 "Re: bug#35443: 27.0.50; Gnus (nnimap) shows \"ghost\" messages 
in summary buffer" "Eric Abrahamsen <eric@ericabrahamsen.net>" "Sat, 27 Apr 
2019 13:47:18 -0700" "<87h8ajjhux.fsf@ericabrahamsen.net>" 
"<w6g1s1ovuew.fsf@kph.uni-mainz.de> <87wojfjxry.fsf@ericabrahamsen.net> 
<w6gwojfo3cy.fsf@kph.uni-mainz.de>" 2609 16 nil
               ((Cc . "35443@debbugs.gnu.org")
                (To . "Ulrich Mueller <ulm@gentoo.org>"))]
        0)
 (32415 32 116
        [32415 "(none)" "(nobody)" "" 
"fake+none+nnimap+dev.gentoo.org:INBOX+32415" nil -1 -1 nil nil]
        0))
Local in buffer *Summary nnimap+dev.gentoo.org:INBOX*; global value is the same.
----------------------------------------------------------------------
gnus-newsgroup-headers is a variable defined in ‘gnus-sum.el’.
Its value is
([32415 "Re: bug#35443: 27.0.50; Gnus (nnimap) shows \"ghost\" messages in 
summary buffer" "Eric Abrahamsen <eric@ericabrahamsen.net>" "Sat, 27 Apr 2019 
13:47:18 -0700" "<87h8ajjhux.fsf@ericabrahamsen.net>" 
"<w6g1s1ovuew.fsf@kph.uni-mainz.de> <87wojfjxry.fsf@ericabrahamsen.net> 
<w6gwojfo3cy.fsf@kph.uni-mainz.de>" 2609 16 nil
        ((Cc . "35443@debbugs.gnu.org")
         (To . "Ulrich Mueller <ulm@gentoo.org>"))]
 [32415 "(none)" "(nobody)" "" "fake+none+nnimap+dev.gentoo.org:INBOX+32415" 
nil -1 -1 nil nil])
Local in buffer *Summary nnimap+dev.gentoo.org:INBOX*; global value is nil

Documentation:
List of article headers in the current newsgroup.
----------------------------------------------------------------------