grml-hostname: improve regex for hostname matching [Closes: issue1005]

Do not trust on output of hostname(1) as this might not
necessarily be what's used inside /etc/hosts. This
is supposed to work on Grml systems as well as on Debian.

While at it also use same formating WRT whitespace chars
when replacing the localhost line(s).

usr_sbin/grml-hostname

@@ -41,14 +41,16 @@ case $retval in
   0)
      echo "$NEW_HOSTNAME" > /etc/hostname
      echo "$NEW_HOSTNAME" > /etc/mailname
-     sed -i "s/^127.0.0.1[ \t]*$OLDHOSTNAME[ \t]*localhost/127.0.0.1       $NEW_HOSTNAME localhost/" /etc/hosts
-     sed -i "s/^::1[ \t]*ip6-localhost ip6-loopback[ \t]*$OLDHOSTNAME/::1     ip6-localhost ip6-loopback $NEW_HOSTNAME/" /etc/hosts
+     sed -ir "s/^\(127.0.0.1\s*\).*localhost.*/\1$NEW_HOSTNAME localhost/" /etc/hosts
+     sed -ir "s/^\(::1\s*\).*ip6-localhost.*/\1ip6-localhost ip6-loopback $NEW_HOSTNAME/" /etc/hosts
+
      POSTFIX=''
      if [ -r /etc/postfix/main.cf ] ; then
        sed -i "s/^mydestination = .*/mydestination = $NEW_HOSTNAME, localhost, localhost.localdomain/" /etc/postfix/main.cf && \
        sed -i "s/^myhostname = .*/myhostname = $NEW_HOSTNAME/" /etc/postfix/main.cf && POSTFIX='
 Configuration of myhostname in /etc/postfix/main.cf has been adjusted as well. Do not forget to restart postfix if necessary.'
      fi
+
      if [ -n "$DISPLAY" ] ; then
        if sudo -u $RUNASUSER xauth add $(xauth -n list | grep "${OLDHOSTNAME}/unix:0" | sed "s|${OLDHOSTNAME}/unix:0|${NEW_HOSTNAME}/unix:0|") ; then
 	  sudo -u $RUNASUSER xauth remove "${OLDHOSTNAME}/unix:0"