[#899] fixed log messages

src/bin/dhcp4/dhcp4_srv.cc

@@ -990,6 +990,12 @@ Dhcpv4Srv::run_one() {
         // second.
 
     } catch (const SignalInterruptOnSelect&) {
+        // Packet reception interrupted because a signal has been received.
+        // This is not an error because we might have received a SIGTERM,
+        // SIGINT, SIGHUP or SIGCHLD which are handled by the server. For
+        // signals that are not handled by the server we rely on the default
+        // behavior of the system.
+        LOG_DEBUG(packet4_logger, DBG_DHCP4_DETAIL, DHCP4_BUFFER_WAIT_SIGNAL);
     } catch (const std::exception& e) {
         // Log all other errors.
         LOG_ERROR(packet4_logger, DHCP4_BUFFER_RECEIVE_FAIL).arg(e.what());