M-ID, gnus-refer-methods and group getting deorganized

[Xavier Maillard <zedek@gnu-rox.org>]

Hello,

I have a big problem.

I consult my USENET news from my own server using a NNTP method.

Say the last message article number here is 50.

Now, imagine my nntp server has done an expiration on its
content.
Imagine then, I want to consult an old post which was given by
its message-id.

If I activate the button in the article buffer, then, Gnus try to
fetch it from my own server (which fails since the server has
expired some contents), then it tries on other server I have
given to Gnus through the gnu-refer-article-method.

It is likely Gnus will find it on the server B. The problem
occurs at this step, if on this server, the corresponding article
is given the article number, say, 200, then Gnus thinks the last
article number seen/read is 200.

Now, whenever I try to get new news on this group, Gnus stays
blind since it considers that I have seen/read all the content
from article ID 50 to 200, which of course, is wrong.

What am I doing wrong ?

I don't have any workaround and this is quite annoying since the
only way to fix that is to empty the whole data for this group
(C-k + delete the whole archived/cached stuff).

Any idea ?

Why Gnus blindly set the last article ID based uniquely on the
article number and not analysing the xref header ? With Xref
parsing, it should have seen that the server B is not server A
and thus, wouldn't have referenced the last article number (and
article count) the way it currently does.
-- 
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Xavier Maillard                  Tel: +33 6 68 04 64 37