Logto2 failing to drop privileges if chdir() fails

[pakal]

I have a very weird bug : when I prepare the deployment of a uwsgi app, by configuring uwsgi but before uploading the dir with application files (so chdir fails), the logto2 file gets created as root instead of the wanted unprivileged user.

Here is the normal error appearing in logs:
--/etc/uwsgi-emperor/_::fitmanager_prod.ini - chdir(): No such file or directory [core/uwsgi.c line 2525]

I've played with log-chown and stuffs, nothing of this changes, but when I create the folder targeted by chdir, all goes back to normal, user and chmod changes work as documented.

in /etc/uwsgi-emperor/vassals-defaults.ini

log-master = on
logfile-chown = yes
logfile-chmod = 644
log-date = %Y-%m-%d_%H:%M:%S
log-reopen = on

in application.ini

include = /etc/uwsgi-emperor/vassals-defaults.ini
uid = www-data
gid = www-data
chdir = /opt/%(appname)/wsgi/
logto2 = /var/log/fitmanager/%(appname).log