FS#2867, ACL processing may fail with utf-8 characters which include byte 'A0'.

More detailed discussion and explanations at https://bugs.dokuwiki.org/index.php?do=details&task_id=2867

Summary. 

Under some circumstances '\s' may match bytes 'A0' & '85'.  These bytes can occur as part of non-space utf8 characters.  Conversely, '\S' may not match these bytes for the same reason.