"git branch -f" corrupt other worktree

[frank kulow <kulow.f@xxxxxxxxxxxxxx>]

git version 2.21.0.windows.1

> /c/tmp/gt (Branch_702091a0)
$ git worktree add ../wt master
Preparing worktree (checking out 'master')
HEAD is now at f534c32 4

> /c/tmp/gt (Branch_702091a0)
$ git branch -D master
error: Cannot delete branch 'master' checked out at 'C:/tmp/wt'

#but this is possible:

> /c/tmp/gt (Branch_702091a0)
$ git branch -f master HEAD

#and the other worktree is now corrupted:

> /c/tmp/wt (master)
$ git status
On branch master
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

        modified:   txt.txt
        deleted:    txtb.txt



greetings f.kulow