Bug 2D Renderer - Outputting incorrect alpha into rendertexture/framebuffer

In my game I have a system that will take a screengrab of a character that is composed of many layers and render it to a render texture so that I can fade out the character without any alpha transparency overlay issues. So the problem is that when I try to do this with the 2D renderer.

So in this example project I have a 2D renderer camera being output to a render texture.

The ordering of the sprites is:
1) BG Quad alpha = 1.0
2) Gradient/Circles

This is what it looks like in the 2D renderer when output directly to the screen:

This is what happens when I render that to a RenderTexture and put it into a transparent (alpha blended) shader.

You can see that the renderer is not outputting a texture that is alpha 1.0 and the subobjects are overwriting the alpha values in the shader. I'm not sure why as I looked at the shader and the blendfunc is SrcAlpha, OneMinusSrcAlpha so I'm left thinking that this is a bug?
Looking at the render texture's alpha channel you can see there there is weird haloing going on with the semi-transparent pixels of the render texture.


I have submitted a Unity bug (1331392) but I'd appreciate any help if I'm missing something here. If I switch the shader from the Sprite-Lit-Default to Sprite-Default (the unlit one) it alpha blends properly and the render texture looks correct.