Getting IsADirectoryError when trying to run examples

[charles-l]

undocker -i -o seems to be broken.

When I try to run the example from the README:

% docker pull busybox
Using default tag: latest
latest: Pulling from library/busybox
Digest: sha256:a9286defaba7b3a519d585ba0e37d0b2cbee74ebfe590960b0b1d6a5e97d1e1d
Status: Image is up to date for busybox:latest
docker.io/library/busybox:latest
% docker save busybox | undocker -i -o busybox busybox
Traceback (most recent call last):
  File "/home/nc/.local/bin/undocker", line 8, in <module>
    sys.exit(main())
  File "/home/nc/.local/lib/python3.8/site-packages/undocker.py", line 99, in main
    open(args.image, 'rb') if args.image
IsADirectoryError: [Errno 21] Is a directory: 'busybox'

Running undocker 7:

% pip3 show undocker
Name: undocker
Version: 7
Summary: Unpack docker images
Home-page: http://github.com/larsks/undocker
Author: Lars Kellogg-Stedman
Author-email: lars@oddbit.com
License: UNKNOWN
Location: /home/nc/.local/lib/python3.8/site-packages
Requires:
Required-by:

[charles-l]

Ohh just checked the code. It looks like no argument is required when reading from stdin anymore? I've just tested it and it seems to work. I'll update the error message to clarify that a bit more...