* Add test that reproduces the issue

* Suggested fix - always save data in sigterm exit flow

* Address test failures on MacOS due to lack of 'Terminated' output on SIGTERM

On the coverage.py metacov, this makes the HTML 5% smaller.

* Put contexts dict in <script> and reveal them using JavaScript

Fixes #1584

* Address review comments

* coverage/htmlfiles/style.css: Align the contexts to the right

* coverage/htmlfiles/style.scss: Match style.css

* coverage/html.py: Fix linting and mypy errors

* two_tests_py.html: make update-gold