Sometimes back face shows front face

[NilsEnevoldsen]

I think what's happening is that the fast path finishes fetching the front-face image before the correct path can abort it. Then the correct path sets the imgUri to the back face, and then the fast path overwrites the imgUri with the front face. This happens because the entire fast path isn't aborted, just the fetch — and it's too late to abort the fetch.

I thought the fetch would be the long-duration part of the fast execution path, but it seems that response.blob() can actually take longer than the fetch().