[BUG] Worktree prune complains about missing path

I’m a bit confused about this, as I thought I understood worktrees :(.

/home/randall/nsgit/test/test dir.mytest/dest git worktree list /home/randall/nsgit/test/test dir.mytest/dest: git worktree list /home/randall/nsgit/test/test dir.mytest/dest     4e901ca [master] /home/randall/nsgit/test/test dir.mytest/dest.wt  4e901ca [dest.wt]

/home/randall/nsgit/test/test dir.mytest/dest: find . -name dest.wt ./.git/logs/refs/heads/dest.wt ./.git/refs/heads/dest.wt ./.git/worktrees/dest.wt /home/randall/nsgit/test/test dir.mytest/dest/.git: cd worktrees/dest.wt /home/randall/nsgit/test/test dir.mytest/dest/.git/worktrees/dest.wt: ls HEAD  ORIG_HEAD  commondir  gitdir  index  logs

/home/randall/nsgit/test/test dir.mytest/dest/.git/worktrees/dest.wt: cat gitdir /home/randall/nsgit/test/test dir.mytest/dest.wt/.git

/home/randall/nsgit/test/test dir.mytest/dest/.git/worktrees/dest.wt: ls HEAD  ORIG_HEAD  commondir  gitdir  index  logs

/home/randall/nsgit/test/test dir.mytest/dest/.git/worktrees/dest.wt: cd ../../../.. /home/randall/nsgit/test/test dir.mytest: rm -rf dest.wt /home/randall/nsgit/test/test dir.mytest: cd dest /home/randall/nsgit/test/test dir.mytest/dest: git worktree prune -v Removing worktrees/dest.wt: gitdir file points to non-existent location

It seems like one or two situations are a problem:
1) I’m using a full path for the worktree. 
2) There’s a blank in my path – deliberate… tests, yanno.

This is git 2.16.2. Could anyone shed some light on this?

Cheers, Randall