I think Coverage.py v4.0 is ready. But to be on the safe side, I’m releasing it as a beta because there have been a ton of changes since v3.7.1. Try it: coverage.py 4.0b1.

Changes since 4.0a6:

• The data storage has been completely revamped. There’s a new API to access the stored data: coverage.CoverageData.
• The XML report has a new missing-branches attribute which breaks conformance to the Cobertura DTD.
• Missing branches in the HTML report now have a bit more information in the right-hand annotations. Hopefully this will make their meaning clearer.
• The private method Coverage._harvest_data is gone. Some third-party tools relied on this. Please test your integrations.
• The speed is back to 3.7.1 levels.

If you are interested, there is a complete list of changes: CHANGES.txt.

Also available is the latest version of the Django coverage plugin: django_coverage_plugin 0.6. This uses the new plugin support in Coverage.py 4.0 to implement coverage measurement of Django templates.