I confirm this on 0.7.1 too.
While this bug doesn't create any problems on most servers, it seems that
Microsoft news server does not like headers with no content. So this server
simply rejects the post with the error message:
 «The 'References:' field requires one or more values»

I asked my newsmaster, the server is INN.

 «The 'References:' field requires one or more values»

Yes, RFC 1036 :

2.2.5.  References

This field lists the Message-ID's of any messages prompting the
submission of this message.  It is required for all follow-up
messages, and forbidden when a new subject is raised.

Replaced plamaiziere@free.fr with null@kde.org due to bounces by reporter

SVN commit 414978 by vkrause:

Don't create empty reference headers on supersede.

CCBUG: 58290


 M  +2 -1      trunk/KDE/kdepim/knode/knarticlefactory.cpp  


--- trunk/KDE/kdepim/knode/knarticlefactory.cpp #414977:414978
@@ -486,7 +486,8 @@
   art->followUpTo()->from7BitString(a->followUpTo()->as7BitString(false));
 
   //References
-  art->references()->from7BitString(a->references()->as7BitString(false));
+  if ( !a->references()->isEmpty() )
+    art->references()->from7BitString( a->references()->as7BitString(false) );
 
   //Supersedes
   art->supersedes()->from7BitString(a->messageID()->as7BitString(false));

SVN commit 414982 by vkrause:

Backport from trunk:
Don't create empty reference headers on supersede.

BUG: 58290


 M  +2 -1      branches/KDE/3.4/kdepim/knode/knarticlefactory.cpp  


--- branches/KDE/3.4/kdepim/knode/knarticlefactory.cpp #414981:414982
@@ -486,7 +486,8 @@
   art->followUpTo()->from7BitString(a->followUpTo()->as7BitString(false));
 
   //References
-  art->references()->from7BitString(a->references()->as7BitString(false));
+  if ( !a->references()->isEmpty() )
+    art->references()->from7BitString( a->references()->as7BitString(false) );
 
   //Supersedes
   art->supersedes()->from7BitString(a->messageID()->as7BitString(false));