Cycles uses the display_space_shader it gets from Blender. When
requested the shader used to be a GPU_SHADER_2D_IMAGE_COLOR, which
set the color uniform incorrectly. This resulted in a yellowish tint
when used.

There are two valid solutions.

1. Set the uniform correctly (vec4 vs vec3)
2. Use GPU_SHADER_2D_IMAGE shader as the color variant is not used.

For this fix I selected to use the GPU_SHADER_2D_IMAGE shader. Not
sure if other render engine uses the color mask.