Move a shared Folder into remote storage

Nextcloud version (eg, 13.0.0):
Operating system and version (CentOS):
Apache or nginx version (Apache):
PHP version (7.*):

Moving a shared folder into a remote folder does not work.

Steps to replicate it:

  1. Log in as Alice. Create a folder. Populate it with a large file. Share it with Bob.
  2. Add a remote storage (tested with WebDAV). Verify that it works.
    3.1. Bob moves the folder into the remote storage.
    3.1. Alice moves the folder into the remote storage.

I would expect both 3.1 and 3.2 to move the folder, clearing most of the space (modulo some management-overhead) in the system of the installation. The sharing-properties and ownership should be preserved.

Instead what happens is: To Bob this action is denied. For Alice it “works”, but Bob now sees the folder once in the Nextcloud installation and again in the remote storage. The one in the remote storage is not shared. Alice sees only the remote folder. If Alice tries to move it back into the Nextcloud installation, this is denied.

Log, when Alice tries to move the folder back:

Fatal	webdav	OCA\DAV\Connector\Sabre\Exception\FileLocked: "Storage/ExampleFolder" is locked

    /var/www/virtual/USER/ - line 158: OCA\DAV\Connector\Sabre\Directory->moveInto('ExampleFolder', 'Storage/ExampleFolder', Object(OCA\DAV\Connector\Sabre\Directory))
    /var/www/virtual/USER/ - line 642: Sabre\DAV\Tree->move('Storage/Vereins...', 'ExampleFolder')
    [internal function] Sabre\DAV\CorePlugin->httpMove(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))
    /var/www/virtual/USER/ - line 105: call_user_func_array(Array, Array)
    /var/www/virtual/USER/ - line 479: Sabre\Event\EventEmitter->emit('method MOVE', Array)
    /var/www/virtual/USER/ - line 254: Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))
    /var/www/virtual/USER/ - line 80: Sabre\DAV\Server->exec()
    /var/www/virtual/USER/ - line 164: require_once('/var/www/virtua...')