extensions: highlight the name of the faulty extensions in the error message This make it easier to understand the message when the extensions name is common. Differential Revision: https://phab.mercurial-scm.org/D11821

extensions: refactor handling of loading error make it reusable We will need this in the next patch. Differential Revision: https://phab.mercurial-scm.org/D11820

extensions: ignore "sub-options" when looking for extensions config suboptions are separated by ":" (see the path one for example). So we dont want to confuse these config with actual extensions. We don't have extensions sub option yet, but I am about to introduce one for making sure an extensions can load. So lets level the floor first. Differential Revision: https://phab.mercurial-scm.org/D11819

automation: support Python 3.10 on Windows Python 3.10 is out and we should support it. This commit teaches the automation code to install and support building for Python 3.10. Differential Revision: https://phab.mercurial-scm.org/D11776

contrib: update Windows environment to Python 3.9.9 Let's keep the environment modern. Differential Revision: https://phab.mercurial-scm.org/D11775

rhg: implement the debugignorerhg subcommand This can be used to inspect the generated pattern, but also to benchmark the time it takes to parse hgignore. Differential Revision: https://phab.mercurial-scm.org/D11722

rhg: refactor to use IgnoreFnType alias more widely Differential Revision: https://phab.mercurial-scm.org/D11818