imply a null node in the DNS tree so a lookup for such a key must clearly fail
and with the current info_hesiod.c it does (after calling hes{,iod}_resolve)
but returns an error that confuses some programs - eg. apache - so shortcut
the process and just return ENOENT for any key starting with "."
Patch will be in am-utils 6.1.
OK'd by christos