Nbdime error on Windows with nbstripout

[fcollonval]

Hey,

We got an issue reported in https://github.com/jupyterlab/jupyterlab-git/issues/471#issuecomment-574326817 when using nbstripout and nbdime on Windows.

I was able to reproduce that issue on the following system:

• Windows 10 x64
• Relevant packages

  # Name                    Version                   Build  Channel
  jupyterlab-git            0.9.0                     dev_0    <develop>
  nbdime                    1.1.0                    pypi_0    pypi
  nbformat                  4.4.0                      py_1    conda-forge
  nbstripout                0.3.7                      py_0    conda-forge
  notebook                  6.0.1                    py37_0    conda-forge
  python                    3.7.6                h5b45d93_1    conda-forge

Digging into that issue, nbdime finds out the filter applied on the notebook by querying the git config command. Then it applies the obtained command on the file before processing with the diff operation.

On Windows, git uses a unix shell. But nbdime with that logic uses the native shell of the OS. And in the particular case of nbstripout, it is failing.

• Call from nbdime

  subprocess.CalledProcessError: Command ''C:/Users/freud/Anaconda3/envs/jlab/python.exe' -m nbstripout' returned non-zero exit status 1.

• Call executed directly in Windows shell:

  (jlab) ...\jupyterlab-git\examples>'C:/Users/freud/Anaconda3/envs/jlab/python.exe' -m nbstripout < demo.ipynb
  ''C:' is not recognized as valid command

The error raises due to the use of single quote in https://github.com/kynan/nbstripout/blob/df6a925b34b067e5ff8a01329a78c86e7f2181a3/nbstripout/_nbstripout.py#L138

Using double quote " removes the error.

[jamesjnadeau]

@kynan Any chance of this getting merged in the near future?

[kynan]

Sorry for the slow response. This will go out in 0.3.8