Latest Debian package hangs on install

I am running Debian unstable and tried to upgrade to the latest version (6.2.3-20231016183016+06cb935ee3 ).

The upgrade starts normally with the following output:
```
Setting up keybase (6.2.3-20231016183016.06cb935ee3) ...
Autorestarting Keybase via systemd for xxxxxx.
```

The client restarts and then the upgrade process hangs (I left one attempt running for about 30 minutes). Quitting the client leads to the following:
```
mkdir: cannot stat ‘/keybase’: Transport endpoint is not connected
chown: cannot access '/keybase': Transport endpoint is not connected
chmod: cannot access '/keybase': Transport endpoint is not connected
dpkg: error processing package keybase (--configure):
installed keybase package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
keybase
```

After some experimentation I found that stopping the keybase.mount service and then running "apt -f install" led to a successful upgrade.

Reproduce the Debian unstable upgrade using the reported Keybase version and inspect the package post-installation step after the systemd restart. Check the keybase.mount service state and the mkdir, chown, and chmod failures for /keybase; use apt -f install to confirm the upgrade completes after the mount is stopped.

Written by the indexing model from the issue text.