Merge branch 'master' into coroutines-tcp

diff --cc src/lua/lua_tcp.c
index 851605be1380875826d00fdce53dc89cc3f43c1f,ce91d78735cc03fdbfb71f54698cdca0702aef49..6b6c32773fc030b1cc9341b56e616368a549cc20
--- 1/src/lua/lua_tcp.c
--- 2/src/lua/lua_tcp.c
+++ b/src/lua/lua_tcp.c
@@@ -401,8 -257,8 +401,8 @@@ lua_tcp_shift_handler (struct lua_tcp_c
                        g_free (hdl->h.r.stop_pattern);
                }
        }
 -      else {
 +      else if (hdl->type == LUA_WANT_WRITE) {
-               if (hdl->h.w.cbref) {
+               if (hdl->h.w.cbref && hdl->h.w.cbref != -1) {
                        luaL_unref (cbd->task->cfg->lua_state, LUA_REGISTRYINDEX, hdl->h.w.cbref);
                }