Merge branch 'es/worktree-cleanup'

Code cleanup around "worktree" API implementation.

* es/worktree-cleanup:
  worktree: retire special-case normalization of main worktree path
  worktree: drop bogus and unnecessary path munging
  worktree: drop unused code from get_linked_worktree()
  worktree: drop pointless strbuf_release()