`Referrer-Policy: no-referrer` breaks `/_logout`?

I have Debian 12 with gitit 0.15.1.0+dfsg-2+b6 and nginx 1.22.1-9 (doing `proxy_pass http://127.0.0.1:5001/`).
I was messing with https://infosec.mozilla.org/guidelines/web_security.html#referrer-policy
I found that with `add_header Referrer-Policy no-referrer always;` in nginx.conf,
when I tried to logout, the /_logout URL returned a 303 redirect back to itself.
This happened over and over until Firefox reached a redirect limit.
It looks like `add_header Referrer-Policy same-origin always;` does not exhibit this issue.

I think if there is no `Referer`, `_logout` should redirect to `/` rather than itself?

I looked at
https://github.com/jgm/gitit/blob/0.15.1.0/src/Network/Gitit/Authentication.hs#L404-L415
but I'm not immediately sure what ought to go in the `dest <- ` to implement "there is no referer".

This is a weird edge case, so I don't mind if you just say "so, don't do that" and close this ticket :-)