bump-leg.py --to <an annotated tag's own id>: the dry run previews it and exits 0, and the validators refuse the real run only after the rewrite #534

The dry run must give the real run's answer before anything is rewritten. For family.py, Brett Heap ruled on 2026-10-14 that bump --to peels an annotated tag's own id, as add --at does; use the same rule here unless there is a reason not to.

From the v1.1.0 triage of the v1.0.0 known limits on #458. One pull request covers the lines below.

Lines

• bump-leg.py --to <annotated tag's own id>: dry run previews it, exit 0; real run refused by validators after rewrite. Where: scripts/bump-leg.py _checked_target_commit, object_present. Effort S; all. On main 3121945: _checked_target_commit checks 40-hex only and object_present asks <id>^{commit}, which peels a tag, so nothing refuses a non-commit before the dry-run return. (source)

Rides along (backlog; tick it here if the same change covers it)

• bump-leg.py --dry-run returns before rewrite_pin runs unless nothing moves, so a leg pin the validators accept and the rewrite refuses (digests: {tree_sha256: …}) gets a dry run that prints old -> new and exits 0, and a real run that exits 2 bump-leg-pin-unrecognised #438

Each line above is marked → this issue on its tracking issue. Tick it there too when this closes.