logind: fd 0 is a valid fd

src/libsystemd-network/sd-dhcp-server.c

@@ -316,7 +316,7 @@ static int dhcp_server_send_udp(sd_dhcp_server *server, be32_t destination,
         int r;
 
         assert(server);
-        assert(server->fd > 0);
+        assert(server->fd >= 0);
         assert(message);
         assert(len > sizeof(DHCPMessage));
 

src/login/logind-session-device.c

@@ -527,7 +527,7 @@ int session_device_save(SessionDevice *sd) {
 }
 
 void session_device_attach_fd(SessionDevice *sd, int fd, bool active) {
-        assert(fd > 0);
+        assert(fd >= 0);
         assert(sd);
         assert(sd->fd < 0);
         assert(!sd->active);