git rebase --update-refs can finish rewriting the current branch and then
fail while updating a local branch that is a symbolic ref. This can happen
during a default-branch rename where refs/heads/main points at
refs/heads/master while users migrate. The failure leaves refs partially
updated even though the main rebase has succeeded.

Resolve local branch decorations before adding update-ref commands. The
first patch skips aliases whose targets are other branches and preserves the
existing handling of the current branch. The second patch keeps aliases to
non-branch refs supported while preventing duplicate and cross-worktree
updates to their resolved targets.

Changes since v2:

 * Skip branch-to-branch symrefs before checked-out handling.
 * Restore the unconditional current-branch skip and keep an owned copy of
   the resolved HEAD name.
 * Check both a non-branch symref alias and its resolved target against
   checked-out reservations.
 * Deduplicate aliases that share a non-branch target.
 * Reserve resolved targets from other worktrees' in-progress update-refs
   state.
 * Split the branch-alias fix and non-branch safeguards into separate
   patches.
 * Rebase onto 48bbf81c29 (The 5th batch).

The focused t3400 and t3404 test suites pass with both the files and
reftable backends.

Son Luong Ngoc (2):
  rebase: skip branch symref aliases
  rebase: guard non-branch symref targets

 branch.c                      | 15 ++++++
 sequencer.c                   | 63 ++++++++++++++++++++-----
 t/t3400-rebase.sh             |  2 +-
 t/t3404-rebase-interactive.sh | 88 +++++++++++++++++++++++++++++++++++
 4 files changed, 155 insertions(+), 13 deletions(-)

base-commit: 48bbf81c29ca9a4479ec7850fe206518682cdb2f

Submitted-As: https://lore.kernel.org/git/pull.2126.v3.git.1784708107.gitgitgadget@gmail.com
In-Reply-To: https://lore.kernel.org/git/pull.2126.git.1779946921.gitgitgadget@gmail.com
In-Reply-To: https://lore.kernel.org/git/pull.2126.v2.git.1780482436865.gitgitgadget@gmail.com