Merge branch 'es/worktree-duplicate-paths'

The same worktree directory must be registered only once, but "git worktree move" allowed this invariant to be violated, which has been corrected. * es/worktree-duplicate-paths: worktree: make "move" refuse to move atop missing registered worktree worktree: generalize candidate worktree path validation worktree: prune linked worktree referencing main worktree path worktree: prune duplicate entries referencing same worktree path worktree: make high-level pruning re-usable worktree: give "should be pruned?" function more meaningful name worktree: factor out repeated string literal