Overrides \Sabre\DAV\Auth\Backend\AbstractBearer::challenge to prevent sending a second WWW-Authenticate header which is standard-compliant but most DAV clients simply fail hard.
Fixes https://github.com/nextcloud/server/issues/5088
Signed-off-by: Lukas Reschke <lukas@statuscode.ch>
Christoph Wurst
Morris Jobke
Lukas Reschke