Merge pull request #21067 from owncloud/fix_20296

apps/files_sharing/ajax/external.php

apps/files_sharing/js/external.js

apps/files_sharing/js/public.js

apps/files_sharing/lib/controllers/sharecontroller.php

apps/files_sharing/templates/public.php

apps/files_sharing/tests/controller/sharecontroller.php

apps/files_sharing/tests/js/externalSpec.js

lib/private/share/helper.php

lib/private/share/share.php

tests/lib/share/helper.php