Changing mipmap levels reactivates last shader

The bug

When you spectate an entity which has a special shader, like a spider, creeper or enderman and then press F5 the shader is disabled. However, it is activated again when you change the "Mipmap Levels".

How to reproduce

1. Start spectating a mob which has a shader, like a spider
2. Press F5 once. This should disable the shader.
3. Change the "Mipmap Levels" in the "Video Settings..."
   → The shader is active again