"git branch --list" learned to show branches that are checked out
in other worktrees connected to the same repository prefixed with
'+', similar to the way the currently checked out branch is shown
with '*' in front.

* nb/branch-show-other-worktrees-head:
  branch: add worktree info on verbose output
  branch: update output to include worktree info
  ref-filter: add worktreepath atom