https://fivethirtyeight.datasettes.com/-/versions reports Datasette version 0.21

This isn't actually correct. The deploy script for that site actually deploys current master using https://github.com/simonw/datasette/archive/master.zip: https://github.com/simonw/fivethirtyeight-datasette/blob/66b4b0dfedd7237bc8c02d3e26d905bca7b84069/Dockerfile#L9

Ideally this would show the current commit hash, but I'm not at all sure if it's possible to derive that from pip install https://github.com/simonw/datasette/archive/master.zip. Is there another mechanism that could be used to reliably pip install current master but still provide access to the most recent commit hash?