Asset bundle memory leak and exception

Hi!

I have some problems related to unloading asset bundles. The problem is that unity leaks memory and throws the exception

Deleting persistent object without writing it first: customassetbundle-91b1e3789f272034fb2e5b6c381c4bce

Stacktrace:

 UnityEngine.AssetBundle:Unload(Boolean)
 Resource:Unload() (at Assets\Resource.cs:192)
 ResourceManager:DiscardResource(String) (at Assets\ResourceManager.cs:103)
 AssetBundleMemoryLeakTest:Update() (at Assets\AssetBundleMemoryLeakTest.cs:73)
 
 [C:/BuildAgent/work/842f9557127e852/Runtime/BaseClasses/BaseObject.cpp line 324] 
 (Filename: Assets/Resource.cs Line: 192)

when unloading an asset bundle under certain conditions.

Steps causing the exception and resulting memory leak:

• load an asset bundle containing a prefab which has a diffuse material and no texture set

• After loading the asset bundle, set a dynamic texture to the diffuse material (manipulate the asset bundle)

• Create one ore more instances of the modified asset bundle game object

• When done, destroy all instances, the dynamic texture and the asset bundle

• This will not free all used resouces, which causes a serious problem when loading and unloading a lot of asset bundles

• Additional to the leaked memory the given exception is thrown, each time AssetBundle.Unload(true/false) is called

I have to modify the game object before instancing it. So assigning the e.g. textures to the created instances is no option.

I am using unity 3.4.1.

I have created a little test project which reproduces the problem. It is attached to the error report:

http://fogbugz.unity3d.com/default.asp?420383_nh181n8ge0fq5u6o

Thanks in advance!