Backport #28266 by @earl-warren
- When crafting the OAuth2 callbackURL take into account `appSubUrl`,
which is quite safe given that its strictly formatted.
- No integration testing as this is all done in Javascript.
- Resolves https://codeberg.org/forgejo/forgejo/issues/1795
(cherry picked from commit 27cb6b7956)
Co-authored-by: Earl Warren <109468362+earl-warren@users.noreply.github.com>
Co-authored-by: Gusted <postmaster@gusted.xyz>
(cherry picked from commit 84e65afffd)
8aee1ae8e9