Unpin nbconvert when upstream fix is released

[desilinguist]

Currently we have pinned nbconvert since v6.0 and above break custom templates. However, there's a fix probably on the way at some point. In the next release, we should remove the pin assuming the fix has been released.

[desilinguist]

A potential fix was recently merged upstream but there has been no release yet. I was curious how we would incorporate this fix so I tried the following:

• In my existing development conda environment, I ran conda remove nbconvert --force. I then installed the latest master from the nbconvert repo as follows: pip install pip install git+https://github.com/jupyter/nbconvert.git.

• I edited the requirements file to remove the nbconvert pin and re-ran pip install -e .

• I made the following changes to reporter.py.

           # set a high timeout for datasets with a large number of features
           report_config = Config({'ExecutePreprocessor': {'enabled': True,
                                                           'timeout': 3600},
  -                                'HTMLExporter': {'template_path': [template_path],
  -                                                 'template_file': 'report.tpl'}})
  +                                'HTMLExporter': {'template_name': 'classic',
  +                                                 'template_file': join(template_path, 'report.tpl')}})

• I made the following changes to report.tpl:

  -{%- extends 'full.tpl' -%}
  +{%- extends 'index.html.j2' -%}

And with these changes, the report generation works fine and the report looks exactly as it does with nbconvert 5.6.1!

Assuming that things do not change drastically between now and whenever the next nbconvert release is, this should be a relatively easy fix.

[desilinguist]

Turns out it isn't that simple. The latest nbconvert is also broken on Windows for Python 3.8. The summary is that nbconvert uses nbclient which uses asyncio and that has an entirely different default implementation on Windows that doesn't include all the same functions! 🤦🏽 On top of that, since we are using nbconvert via its API and not the command line, we need to manually include the workaround in our code too. I will do this as part of this issue.

A fuller description of the issue can be found here and here.