[turba] Current state of affairs with OSX 10.10 and IOS 8.1

[Registration]

Server settings:

Turba 4.2.2
Horde 5.2.1
Imp 6.2.2
Email address as login user name
Imp for authentication, connecting to dovecot IMAP server via localhost, SSL
Apache 2.2.22 with VirtualHosts, using SSL forward via Redirect permanent directive to the https version of all horde directories
www-server is owner of all horde directory, unchanged .htaccess files
PHP5 5.4.4, standard configuration
Debian Wheezy, up to date



IOS 8.1:

Contacts sync both ways, multiple address books are shown, 
new contacts can be created by the client in one of the address books
(chosen somehow, didn’t test the influence of the $conf[client][addressbook] setting).



OSX 10.10:

Username: emailaddress
Server address: https://servername/rpc.php/principals/emailaddress/
I can drop emailaddress/ and even /emailaddress/ from the last line, 
even write /rpc.php/turba instead, and it still accepts the account creation, 
with always the same result as server path: rpc.php/principals/emailaddress/
If I use some completely wrong address, it does not accept the credentials, however.

In any accepted case, it does not sync. No error on client or server side (despite server debug log level).
New entries created in the OSX client result in CoreDAVHTTPStatusErrorDomain 500.

I tested setting $conf[client][addressbook] and $conf[gal][addressbook] to None 
or some addressbook before adding the account to the client, with no change.