shader issue when upgrading project from Unity4 to 5

I'm in the middle of upgrading a project from Unity4 to 5.
I had skyboxes which used a tint color, in the shader it would multiply the skybox with this color.
Now in Unity5 it seems it adds the color instead.
I looked at the shader code, and all it does with the tint color is:
Color [_Tint]
(in the SubShader before the passes)

So is this intentional behaviour, or is it a bug?
I can't see why Unity would decide to make it work that way.

 

anyone?

 

i'm having the issues in Shader. When upgrading from Unity 4 to 5
Shader error in 'Transparent/Cutout/Soft Edge Lit Double Sided': 'LightingLambert': cannot implicitly convert from 'min16float3' to 'struct UnityGI' at line 98 (on gles3)

Compiling Vertex program with DIRECTIONAL LIGHTMAP_OFF DIRLIGHTMAP_OFF DYNAMICLIGHTMAP_OFF
Platform defines: UNITY_NO_SCREENSPACE_SHADOWS UNITY_ENABLE_REFLECTION_BUFFERS UNITY_PBS_USE_BRDF1 UNITY_SPECCUBE_BOX_PROJECTION UNITY_SPECCUBE_BLENDING

 

How is that realted to the problem I'm having?