Exporting GAN learner crashes

When I try to export a GANLearner it fails the assertion at fastai/optimizer.py:125, i.e.:

assert len(sd["state"])  == sum([len(pg) for pg in self.param_lists])

I replicated this by running this notebook fastai/lesson7-wgan.ipynb at master · fastai/fastai · GitHub and adding learn.export() at the end and it crashes there. I’m able to save and load the model with learn.save(path) and learn.load(path) but I thought it would be good for the export method to work too (or at least give a more helpful error message).

Does anyone know if I’m doing something wrong? Or is this something that would be good for someone to look at?