git-old-branches tripped up by worktree

[jakkanen]

Given following preparation:

git init /tmp/myrepo
cd /tmp/myrepo
date > file
git add file
git commit -m "frist"
git worktree add /tmp/myworktree

The git-old-branches command will print an unexpected error:

$ git old-branches
log + myworktree -1 --format=%at --fatal: bad revision '+'

The plus sign is mentioned in git-branch documentation:

Any branches checked out in linked worktrees will be highlighted in cyan and marked with a plus sign.