How to reproduce:

1. Open the attached project in Unity 4.x and the only scene in it.
2. Observe first pass writes to the depth buffer, so non of the inner parts can be seen.
3. Open the same project in Unity 5.x
4. Notice, that now inner parts can be seen even the same "Transparent/Diffuse ZWrite" shader is used.

Expected behavior: In Unity 5.x release "Transparent/Diffuse ZWrite" shader fills depth buffer same as in 4.x.
Actual behavior: Compared to 4.x writing to depth buffer in Unity 5.x is very different.

Reproducible: 5.5.0a5, 5.4.0f3, 5.3.6p2, 5.2.4f1
Not reproduced: 4.7.2f1