Login seems to break automatic git-pull of repo

I have a URL to a TLJH server of the form

https://SERVERNAME/hub/user-redirect/git-pull?repo=https://github.com/REPO&urlpath=apps/REPO/index.ipynb

This does a git pull of the REPO and then executes the index.ipynb notebook (via appmode package). This approach made the use the notebooks easy for our non-majors who just need to execute the notebooks, not understand their code.

I had to switch from an external OAuth authenticator (`oauthenticator.auth0.Auth0OAuthenticator`) to the default `FirstUseAuthentication`. This change was necessary because our campus' default email addresses are now too long to use for account names.

The problem is now, when a user logins, it just dumps them to the blank Jupyter notebook page instead of executing git-pull and appmode. In essence,

https://SERVERNAME/hub/user-redirect/git-pull?repo=https://github.com/REPO&urlpath=apps/REPO/index.ipynb

gets treated as

https://SERVERNAME/hub/

Any ideas why this doesn't work with the `FirstUseAuthentication`? Interestingly, once they are logged in, the git-pull URL works, but any attempt for a user who isn't already logged in to use it fails.

Juan