python wheels: do not "expand"

[haampie]

Implement a no-op decompressor for "whl" to make expand=False redundant.

Should be future-proof in the sense that we can identify the mime type of these
file as zip, and discriminate between wheel vs any other zip file by looking for a
*.dist-info/WHEEL file. For now it's file extension based though.

[spackbot-app]

Hi @haampie! I noticed that the following package(s) don't yet have maintainers:

• py-azureml-automl-core
• py-azureml-core
• py-azureml-dataprep
• py-azureml-dataprep-native
• py-azureml-dataprep-rslex
• py-azureml-dataset-runtime
• py-azureml-pipeline
• py-azureml-pipeline-core
• py-azureml-pipeline-steps
• py-azureml-telemetry
• py-azureml-train
• py-azureml-train-automl-client
• py-azureml-train-core
• py-azureml-train-restclients-hyperdrive
• py-climate
• py-dotnetcore2
• py-igor2
• py-installer
• py-intel-openmp
• py-itk
• py-jupyterlab-pygments
• py-jupyterlab-widgets
• py-lightning-api-access
• py-opencensus-context
• py-setuptools
• py-shiboken2
• py-thop
• py-tuswsgi
• py-wheel
• py-x21

Are you interested in adopting any of these package(s)? If so, simply add the following to the package class:

    maintainers("haampie")

If not, could you contact the developers of this package and see if they are interested? You can quickly see who has worked on a package with spack blame:

$ spack blame py-azureml-automl-core

Thank you for your help! Please don't add maintainers without their consent.

You don't have to be a Spack expert or package developer in order to be a "maintainer," it just gives us a list of users willing to review PRs or debug issues relating to this package. A package can have multiple maintainers; just add a list of GitHub handles of anyone who wants to volunteer.

[adamjstewart]

This is cool. If for whatever reason it doesn't get approved, another thing I've thought about is allowing expand = False at the package level like we do for most other version parameters (url, git, submodule, etc.).

[haampie]

I don't think that's going to be necessary. Only use case for extracting wheels is patching, but at that point we should probably also install them manually instead of relying on pip.

[alalazo]

LGTM, once unit tests are updated 🙂