Bump auth zone serial when reloading /etc/hosts and friends.

CHANGELOG

@@ -20,6 +20,10 @@ version 2.77
  	    Fix problem with --dnssec-timestamp whereby receipt
             of SIGHUP would erroneously engage timestamp checking.
 	    Thanks to Kevin Darbyshire-Bryant for this work.
+
+	    Bump zone serial on reloading /etc/hosts and friends
+	    when providing authoritative DNS. Thanks to Harrald
+	    Dunkel for spotting this.
 	
 
 version 2.76

src/dnsmasq.c

@@ -1226,6 +1226,8 @@ static void async_event(int pipe, time_t now)
     switch (ev.event)
       {
       case EVENT_RELOAD:
+	daemon->soa_sn++; /* Bump zone serial, as it may have changed. */
+
 #ifdef HAVE_DNSSEC
 	if (daemon->dnssec_no_time_check && option_bool(OPT_DNSSEC_VALID) && option_bool(OPT_DNSSEC_TIME))
 	  {