Fix "Uninitialized string offset: 0 at \/media\/psf\/stable9\/lib\/private\/URLGenerator.php#224"
Fix "Uninitialized string offset: 0 at \/media\/psf\/stable9\/lib\/private\/URLGenerator.php#224"

The URLGenerator doesn't support `` as target for absolute URLs, we need to link to `/` thus.

Regression introduced with https://github.com/nextcloud/server/commit/46229a00f39e507249dbe3ceb7507277da3fa4f8

Signed-off-by: Lukas Reschke <65adda4326914576405c9e3a62f4904d96573863@statuscode.ch>

michaelletzgus/nextcloud-server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server,nextcloud/server,nextcloud/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server