Why LPIPS evaluation is removed?

[skynbe]

I would like to know if there is any problem in evaluating LPIPS.

[jonbarron]

LPIPS evaluation required calling out to TensorFlow Hub, and that caused a breakage in the code at some point. Instead of fixing the breakage we thought it would be easier to just delete the problematic code, especially since LPIPS seemed to be strongly correlated with SSIM. You can try to undo the old PR, the issue with TF-hub might be fixed by now.