Problems with GSSAPI authentication

[Jonas Oberg <jonas@gnu.org>]

I'm trying to use GSSAPI (Kerberos V) authentification in Gnus against
a remote host. I've installed and configured everything so that the
imtest program works flawlessly from the command-line.  Like this;

$ imtest -m gssapi imaphost
C: C01 CAPABILITY
S: * OK imaphost IMAP4rev1 v12.250 server ready
S: * CAPABILITY IMAP4 IMAP4REV1 NAMESPACE IDLE SCAN SORT MAILBOX-REFERRALS LOGIN-REFERRALS AUTH=GSSAPI AUTH=LOGIN THREAD=ORDEREDSUBJECT
S: C01 OK CAPABILITY completed
[...]
C: A01 AUTHENTICATE GSSAPI
[...]
S: A01 OK AUTHENTICATE completed
Authenticated.

Now, when I try to connect to imaphost in Gnus, it correctly launches
imtest with the correct parameters (imtest -m gssapi -u jonas -p 143 imaphost).
I can tell from the logs on the imaphost that Gnus connects and is
authenticated, but then nothing happens. It just sits there doing nothing.
A strace on the imapd on the server tells me that it's waiting for Gnus
to issue a command, but this seems to never happen.

Any suggestions?