Wrong behavior of bkr2ipynb on Windows

I have a directory with beaker notebooks and I want to batch convert it. `python -m beakerx.bkr2ipynb *.bkr` fails with error `OSError: [Errno 22] Invalid argument: '*.bkr'`. If I try to convert single notebook, it creates a file called `.ipynb` without a name. If I add a name to it, the file becomes readable and seems to be alright.