This “bake texture” render is with simply N -> Cd in the shader using “uv to surface” as unwrap mode. There's no unshared edges within the uv patch and still you can find some black pixels every now and then. In those, the alpha is black too even though it's set to a constant = 1 in the shader. If I add a value of .00001 to the uv the dead pixels jump around randomly and I can make them fade away by increasing the pixel samples.

What can cause the render to fail to render pixels like this?