This method is called when efun process_string() is used without a
current object (e.g. from notify_fail method). The current object
will be set to the current command giver, and will receive the euid
returned from this function.
If strict-euids, this function must exist and return a string.
Otherwise the function is optional and/or may return 0.
Since 3.2.1, get_bb_uid() is needed just for process_string()
if no this_object() is present.
uids(C), creator_file(M), creator(E), get_master_uid(M)