{
		engine = asCreateScriptEngine();
		engine->SetMessageCallback(asMETHOD(CBufferedOutStream, Callback), &bout, asCALL_THISCALL);
		bout.buffer = "";

		mod = engine->GetModule("test", asGM_ALWAYS_CREATE);
		mod->AddScriptSection("test",
			"namespace X {"
			"shared class A"
			"{"
			"}"
			"shared class B : A"
			"{"
			"  void bar() {}"
			"}}"
         );
		r = mod->Build();
		if (r < 0)
			TEST_FAILED;

		asIScriptModule *mod2 = engine->GetModule("test2", asGM_ALWAYS_CREATE);
		mod2->AddScriptSection("test",
			"namespace X {"
			"external shared class A;"
			"external shared class B;"
			"}"
			"namespace Y {"
			"class Test : X::A"
			"{"
			"  X::B b;"
			"  void foo() { b.bar(); }"
			"}}"
		);
		r = mod2->Build();
		if (r < 0)
			TEST_FAILED;

		CBytecodeStream bc1("test");
		r = mod->SaveByteCode(&bc1); assert(r >= 0);
		if (r < 0)
			TEST_FAILED;

		CBytecodeStream bc2("test2");
		r = mod2->SaveByteCode(&bc2); assert(r >= 0);
		if (r < 0)
			TEST_FAILED;

		mod2->Discard();

		// game loop
		for (unsigned i = 0; i < 10; ++i) {
			engine->GarbageCollect(); // run DeleteDiscardedModules();
		}

		mod2 = engine->GetModule("test2", asGM_ALWAYS_CREATE);
		r = mod2->LoadByteCode(&bc2);
		if (r < 0)
			TEST_FAILED;

		if (bout.buffer != "")
		{
			PRINTF("%s", bout.buffer.c_str());
			TEST_FAILED;
		}

		engine->ShutDownAndRelease();
	}

When you execute the above, the following will be output.

 (0, 0) : Error   : LoadByteCode failed. The bytecode is invalid. Number of bytes read from stream: 255

Similar to this case, it seems that problems will occur with virtual method restore this time.

Thank you always.
I checked this problem at revision 2506, but unfortunately it was not solved.