Version Control in CI

Upgrading Mercurial

Upgrading Mercurial in CI requires touching a handful of different components.

Vendored robustcheckout

The robustcheckout Mercurial extension is used throughout CI to perform clones and working directory updates. The canonical home of the extension is in the https://hg.mozilla.org/hgcustom/version-control-tools repository at the path hgext/robustcheckout/__init__.py.

When upgrading Mercurial, the robustcheckout extension should also be updated to ensure it is compatible with the version of Mercurial being upgraded to. Typically, one simply copies the latest version from version-control-tools into the vendored locations.

The locations are as follows:

In-tree: taskcluster/scripts/robustcheckout.py
ronin_puppet: https://github.com/mozilla-platform-ops/ronin_puppet/blob/master/modules/mercurial/files/robustcheckout.py, https://github.com/mozilla-platform-ops/ronin_puppet/blob/master/modules/win_mozilla_build/files/robustcheckout.py, https://github.com/mozilla-platform-ops/ronin_puppet/blob/master/modules/linux_mercurial/files/robustcheckout.py
taskgraph: https://github.com/taskcluster/taskgraph/blob/main/src/taskgraph/run-task/robustcheckout.py

Debian Packages for Debian and Ubuntu Based Docker Images

taskcluster/kinds/packages/debian.yml and taskcluster/kinds/packages/ubuntu.yml define custom Debian packages for Mercurial. These are installed in various Docker images.

To upgrade Mercurial, typically you just need to update the source URL and its hash in this file.