gvfs: mishandling of file's user and group ownership in daemon/gvfsbackendadmin.c due to unavailability of root privileges

An issue was discovered in GNOME gvfs 1.29.4 through 1.41.2. daemon/gvfsbackendadmin.c mishandles a file's user and group ownership during move and copy with GFILECOPYALLMETADATA operations from admin:// to file:// URIs, because root privileges are unavailable...