Stalls, never gets to "About to upload 1 files"

[riddell-stan]

I'm running:

python -m wheelhouse_uploader upload --local-folder ${TRAVIS_BUILD_DIR}/wheelhouse/ --no-update-index --region=${WHEELHOUSE_UPLOADER_REGION} wheels

Occasionally (often) nothing happens. I don't even get to "About to upload 1 files".

This is happening on osx and linux builds on travis. Could be a travis networking error. But if it's a networking error perhaps there should be a timeout (5m?) added at some stage?

Example: https://travis-ci.org/stan-dev/pystan-wheels/jobs/421273119