[horde] CalDAV + IMP Authentication issues (or how to disable list capability for imp authentication driver?)

[Martin Felis]

Hello everyone,

I am very happy with the new Horde and also adding CalDAV support is a 
feature I am very glad to see in the newest Horde.

The authentication for my Horde installation is set-up such that I let 
imp do the authentication.

The problem is, that when accessing the CalDAV-Subscribe-Address I get 
the error message:

<d:error>
   <s:exception>Sabre\DAV\Exception\NotFound</s:exception>
   <s:message>User martin does not exist</s:message>
<s:sabredav-version>1.8.4</s:sabredav-version></d:error>

After playing around with the file 
/usr/share/php/Horde/Dav/Principals.php I figured that the auth 
capability 'list' is enabled (near line 90). This is however this cannot 
be the case as I doubt that imp has such a deep knowledge of my system.

When commenting out the lines it works. Also when switching to the IMAP 
authentication driver, however in this case I have to enter my 
login-details twice which I do not enforce on my users.

Is there any way to tell the imp authentication driver that the 'list' 
capability is disabled?

Best regards, and thanks again for Horde!

Martin