[PATCH 0/3] extend --ignore-other-worktrees to 'rebase', add hints

The old 'workdir' contribution script was removed from git upstream in May 2025, as it is largely superseded by the 'worktree' command.

One significant difference between the old script and the command is that 'git' refuses to checkout or rebase branches that are already checked out in another worktree. My understanding of the reasoning is that users may be surprised when a clean worktree becomes dirty as its index is changed from another worktree. However, this safety net adds a mental burden to worktree users, as they have to keep the other worktrees in mind when moving branches. Old goats like me who are used to the old 'workdir' script find this restriction somewhat painful.

See the discussion thread
  https://lore.kernel.org/git/5580aa89-09f1-426e-8483-c99481c998ab@gmail.com/
about this transition.

The present patch series tries to provide a smoother migration path for supporters of worktree independence:

 - when 'checkout' refuses because the branch is used in another worktree,
   display a 'hint' that mentions the possibility of using '--detach'
   instead, and the '--ignore-other-worktrees' option to proceed anyway.

 - add support for '--ignore-other-worktrees' in 'rebase' as well, with
   a similar hint.

In the future I would be interested in adding an option 'branch.ignoreOtherWorktrees' to be able to ignore other worktrees globally.

Note: this is my first experience submitting a patch to the Git project, so
I apologize in advance for any mishap and welcome beginner-level feedback.

Cc: Junio C Hamano <gitster@pobox.com>
Cc: D. Ben Knoble <ben.knoble@gmail.com>
Cc: Phillip Wood <phillip.wood@dunelm.org.uk>

Signed-off-by: Gabriel Scherer <gabriel.scherer@inria.fr>

Gabriel.Scherer (3):
  checkout: provide hint when failing due to another worktree
  rebase: support --ignore-other-worktrees
  rebase: hint when failing on branch used by another worktree

 Documentation/config/advice.adoc |  3 +++
 Documentation/git-rebase.adoc    |  6 ++++++
 advice.c                         |  1 +
 advice.h                         |  1 +
 branch.c                         | 13 +++++++++++--
 branch.h                         |  4 ++++
 builtin/checkout.c               | 12 ++++++++++--
 builtin/rebase.c                 | 19 ++++++++++++++++++-
 t/t3400-rebase.sh                |  4 +++-
 9 files changed, 57 insertions(+), 6 deletions(-)