The session-activity announcement schema gains an optional branch field, populated only for providers whose changes lack their own head branch, currently Gerrit, so a host can place the change on the right checkout.
PR/change announcements can carry a branch name for Gerrit
Change announcements can carry a branch name for providers like Gerrit whose changes have no head branch.
Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
Git IntegrationArea: what it touches
Internal ChangesKind: in v2.1.259,
Internal ChangesSection of the release