A bug about the cityscapes_demo.py

[oak-JHCheng]

HI, thanks for the great repo.

I'm doing some inference with the script cityscapes_demo.py
It can generate good result, but only semantic seg result.

I changed the param eval='panoptic' or 'semantic' or 'instance' or 'segment':
result = inference_detector(model, img_, eval='panoptic')
the result always the same (semantic segmentation result) like this:

So the param eval can't work?
I want to know the reason and the other question:
can the demo scripts be used as inference tools for other pictures?

Thanks