Set chech_for_unused_update_ops to False by default.

[Gsunshine]

A bug is reported in SAGAN that check_for_unused_update_ops=True raise a ValueError. I find it suppose all ema buffers in bn to be unused update ops.

However there is no API in current SAGAN example to disable this check since it has ben encapsulated. So I set the kwarg in original tfgan implementation https://github.com/tensorflow/gan/blob/master/tensorflow_gan/python/train.py#L974 to False. The code runs normally then.

My tf version is 2.0.0 and tfgan is the current version.

[Gsunshine]

Update: The bug is reported on 1080Ti with build-in GPU estimator. When I run the code on TPUs, everything is fine.

Hope this issue could help you!

[joel-shor]

Do you experience this with TF 1.X?