OC 9.1: Cannot share subscribed calendars

Steps to reproduce
1. Login as administrator (or every other user)
2. Subscribe to a calendar (like http://www.ifeiertage.de/he-zsk.ics )
3. Click on the "share" icon and enter an existing user or group

Expected behaviour
State should go to "shared" as seen in sharing a "normal" calendar.
Furthermore it should show a link for external access (for Thunderbird Calendar)

Actual behaviour
Nothing happens. Calendar is not shared and can't access it from Thunderbird.

Server configuration
Operating system: Debian GNU/Linux 7
Web server: Apache
Database: Built-In SQLite
PHP version: PHP 5.4.45-0+deb7u4
ownCloud version: 9.1.1 (stable)
Updated from an older ownCloud or fresh install: Updated from 9.0.4 from

Special configuration: Nothing.

Integrity status for oC9+

No errors have been found.


 Fatal 	webdav 	Exception: {"Message":"HTTP\/1.1 501 There was no handler found for this \"POST\" method","Exception":"Sabre\\DAV\\Exception\\NotImplemented","Code":0,"Trace":"#0 \/var\/www\/owncloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#1 \/var\/www\/owncloud\/apps\/dav\/lib\/Server.php(172): Sabre\\DAV\\Server->exec()\n#2 \/var\/www\/owncloud\/apps\/dav\/appinfo\/v2\/remote.php(29): OCA\\DAV\\Server->exec()\n#3 \/var\/www\/owncloud\/remote.php(164): require_once('\/var\/www\/ownclo...')\n#4 {main}","File":"\/var\/www\/owncloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php","Line":462,"User":"admin"}

Bug or really "not implemented"?

Btw: how often are subscribed calendars refreshed? Didn't found any settings for this feature.



this feature is currently not implemented: