How to use Environment variables in app.ini

Hi

Real simple question.

Q; How do you use environment variables in app.ini ?
Why: I’ve been re-arranging placement of repo and custompaths and don’t want hardwired usernames in my app.ini as before.

Let’s use ROOT as an example: I tried ROOT = ${GITEA_WORK_DIR}/repos, $HOME/repos, etc… but had no luck. Oddly enough leaving just ROOT = repos seems to work and I can log in and see everything. However from reading the help it would seem it would need absolute path, although it seems like its automatically pre-pended ${GITEA_WORK_DIR} ? Or is it a left over from previous gitea session in gitea.db?