aarch64 build issues

[TomAugspurger]

A few issues with the aarch64 build:

1. We're building a wheel for NumPy 1.14.5. I think the idea is to build against the oldest ABI-compatible NumPy for that Python version, but NumPy doesn't have aarch64 wheels for 1.14.5. Can / should NumPy build wheels? I think not, since IIRC there were some patches in 1.17.x or 1.18.x to get ARM64 support. So should pandas build against a different version of NumPy? Or do we just live with building NumPy wheels too? (cc @mattip if you have thoughts)
2. I don't see any aarch64 wheels at https://anaconda.org/scipy-wheels-nightly/pandas/files yet. @janaknat can you look into that?

[mattip]

So should pandas build against a different version of NumPy?

Yes, at least until the gap closes. Make you lives easier, since older versions will have problems.

Or do we just live with building NumPy wheels too?

No.

[janaknat]

@TomAugspurger The files show up at https://anaconda.org/multibuild-wheels-staging/pandas/files on push. The scipy-wheels-nightly is used when the build is initiated by a cron job. Is the nightly builds a cron job?

[janaknat]

I'll create a PR to use the latest numpy. Should cut down on build times further. @TomAugspurger Timeline on when the aarch64 wheels will show up in pypi?

[TomAugspurger]

I think the nightly (cron job) builds are supposed to go to https://anaconda.org/scipy-wheels-nightly/pandas. Release builds on master should go to https://anaconda.org/multibuild-wheels-staging/pandas.

Looks like wheels were skipped for the recent 1.1.3 release. I suppose that's because it's version is specified in the travis file rather than the azure pipeline yaml file.

So short-term we'll need to manually update the pandas version in .travis.yaml file.

Long-term we need to update https://github.com/pandas-dev/pandas-release/blob/70ff1463db0e07bcabf85b1a1ba5b20efd3a01f1/scripts/wheels.sh to also update .travis.yaml. Any help here would be appreciated @janaknat.

[janaknat]

@TomAugspurger Weird. There is a cron check in .travis.yml. Does the Travis account have a cron job scheduled? I see azure-pipelines.yml has the cron job listed up top.

I will create a PR updating the pandas-version here. I'll also open a PR for the pandas-release.

[TomAugspurger]

FYI @janaknat I've uploaded the aarch64 wheels for pandas 1.1.3: https://pypi.org/project/pandas/1.1.3/#files.

If you're able to, an update to https://github.com/pandas-dev/pandas-release/blob/70ff1463db0e07bcabf85b1a1ba5b20efd3a01f1/scripts/wheels.sh would be appreciated, so that we don't forget to bump it in the next release.

I'm not sure what's up with the nightly build. There was a cron job, but it may have been from the old config. I just recreated it.