Terms of Service modal doesn't show up if you log in with OAuth (Google/Twitter/Github etc)

If you log in using OAuth the modal "You must accept the terms and conditions" never appears.

I only know I haven't accepted it yet because I have a mirror that's been failing for months and I can't seem to get it to succeed. The error message says "GitLab: You (@_stark) must accept the Terms of Service in order to perform this action. Please access GitLab from a web browser to accept these terms.<br>". However even if I log out and back in using OAuth as I normally do I never get the modal.

There's no indication anywhere in the UI or the error message of how to trigger this modal and accept the terms and conditions. If Google hadn't found me a related issue that contained the raw link to the modal I would be completely stuck.

Also, btw, the "<br>" at the end of the error message produces a stray literal "
" in the error message in the UI.