`dtolnay/rust-toolchain` is not a dependency in the sense Dependabot
means: it is versioned by the Rust release it installs, and the tag we
pin is the toolchain CI is pinned to on purpose — precommit.sh runs the
same one locally, so a lint that passes on a developer's newer default
cannot pass CI by accident.
Read as semver, those tags produced a 1.97.0 -> 1.100.0 proposal, a Rust
version that does not exist. Every such PR 404s on toolchain download
across all eight repos and regenerates weekly: eight permanently-red PRs
that promote.yml then has to special-case when it decides whether dev is
green.
freemkv already carries this ignore; this is the same block in the other
seven, so the fleet stays uniform. Bumping the toolchain stays a
deliberate, all-eight-repos change made by hand together with
precommit.sh.
Version updates were never configured here -- only security alerts, which
report but never open a pull request. So the absence of Dependabot PRs was
not "nothing to update", it was "nothing was checking".
Updates target `dev`, never `main`. main is a release pointer that
release.sh moves to each tag, so a bot commit on it would put work there
that no tag contains -- the exact state that aborted the 1.6.2 cascade at
its last step, and pointing a scheduled bot at main would recreate it
weekly.
Minor and patch bumps are grouped into one PR rather than one per crate:
eight repos times a handful of dependencies is a volume nobody reads, and
an unread PR queue is indistinguishable from no updates at all.
The freemkv crates are excluded. They depend on each other by git tag,
re-pinned by release.sh inside the release commit, and Dependabot cannot
see that cascade -- a PR bumping one could pin a version whose tag does
not exist yet.
Matthew Jackson