RenderInRenderTarget doesn't restore state properly

[metalgearsloth]

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So there's render target and bound render target. RenderInRenderTarget restores both fields to the boundrendertarget (via BindTargetFull) which means if you had an existing rendertarget it would get bulldozed.

AFAIK the only area this has ever been an issue was when I added an overlay draw into the lighting drawing. I got a fix in the works unless it gets fixed on master before then.