Merge branch 'nd/do-not-move-worktree-manually' into maint

"git worktree" had a broken code that attempted to auto-fix
possible inconsistency that results from end-users moving a
worktree to different places without telling Git (the original
repository needs to maintain backpointers to its worktrees, but
"mv" run by end-users who are not familiar with that fact will
obviously not adjust them), which actually made things worse
when triggered.

* nd/do-not-move-worktree-manually:
  worktree: stop supporting moving worktrees manually
  worktree.c: fix indentation