esp8266/moduos: Populate release field of uname in case it was GC'd.

esp8266/moduos.c

@@ -58,10 +58,9 @@ STATIC mp_obj_tuple_t os_uname_info_obj = {
 };
 
 STATIC mp_obj_t os_uname(void) {
-    if (os_uname_info_obj.items[2] == NULL) {
+    // We must populate the "release" field each time in case it was GC'd since the last call.
     const char *ver = system_get_sdk_version();
     os_uname_info_obj.items[2] = mp_obj_new_str(ver, strlen(ver), false);
-    }
     return (mp_obj_t)&os_uname_info_obj;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(os_uname_obj, os_uname);