Worktree silently deleted on git fetch/gc/log

Hello,

with git 2.16.2 I have two repositories:

A (branch master) and B (branch g) which is a worktree of the first.

This has always forked fine until yesterday, when I did:

/git/B g>$ git fetch
remote: Counting objects: 29, done.
remote: Compressing objects: 100% (6/6), done.
remote: Total 29 (delta 19), reused 25 (delta 19), pack-reused 4
Unpacking objects: 100% (29/29), done.
 From https://...
    13e4c55a0..02655d5fb  g -> origin/g
    c37a3ca25..bc7888511  master -> origin/master
Auto packing the repository in background for optimum performance.
See "git help gc" for manual housekeeping.
/git/B g<>$ git log -p origin/g
fatal: Not a git repository: /git/A/.git/worktrees/B
/git/B$

Please note that on the second last prompt there is <>, so that git-prompt has found the neccessary information and this was this was later deleted - by 'gc' or 'log'.

I guess somebody who knows the code in detail can easily fix this.

What would be the procedure to restore the /git/A/.git/worktrees/B structure?

Kind regards
   Dilyan