BLD Creates and test a source distribution

[thomasjpfan]

Resolves #31

Cython needs to be installed for 0.22.X since pyproject.toml is only on master and will be released with 0.23.

CC @ogrisel

[adrinjalali]

Thanks @thomasjpfan

[jnothman]

Otherwise LGTM... untested.

[jnothman]

posix.xml just has condition: variables['TOKEN']

[jnothman]

Otherwise LGTM... untested.

[mattip]

In MacPython/numpy-wheels#78 I needed to mangle the $TOKEN handling a little differently in order to get the non-uploading PRs (ones from a fork of this repo that have no access to the secrets) to respect the conditional upload, especially on macOS (not relevant for this PR). The steps were:

• change the local secret-reflected name by adding the prefix MAPPED_
• add another check if [ "$TOKEN" == "" -o "${TOKEN:0:7}" == "\$(NUMPY" ]; then ... because a missing secret resulted in $TOKEN having the value $(NUMPY_*_UPLOAD_TOKEN rather than ""

I think this is due to the bash shell equivalent being substandard on macOS, but was wondering if you ran into anything like this as well?

[thomasjpfan]

In our case, we use a pretty long condition:

scikit-learn-wheels/azure/posix.yml

Line 114 in 8859f4f

condition: and(succeeded(), eq(variables['SKIP_BUILD'], 'false'), ne(variables['Build.Reason'], 'PullRequest'), variables['SCIKIT_LEARN_NIGHTLY_UPLOAD_TOKEN'], variables['SCIKIT_LEARN_STAGING_UPLOAD_TOKEN'])

to make sure not to update when the token is not defined. (Which I need to update this PR with)

[adrinjalali]

Now that we're releasing 0.23, should we merge this (after fixing the merge conflicts)?

[thomasjpfan]

Note this PR places the BUILD_COMMIT in azure-pipelines.yml, which means it is the only place we need to update to change the version.

(Did not want to have another BUILD_COMMIT in the sdist yaml.)

[adrinjalali]

Thanks @thomasjpfan