Evaluation, build, test, and deploy jobs now fetch only the commit they are building or running, not every commit it descends from. For a repository with a long history that is much less to download, and the fetch is the first thing every job does.
A new shallow-clone option in nix-ci.nix controls it.
Set shallow-clone = false for a flake that reads self.revCount, which has no history to count when only one commit is fetched.
A test or deploy job that runs in-repo still fetches the whole history, because it clones the repository and a clone has no depth control.