Log when wrong person uses invitation

gregui/authentication/auth_backends.py

@@ -622,6 +622,13 @@ class GregOIDCBackend(ValidatingOIDCBackend):
                         not inv_person.registration_completed_date
                         and not name_diff_too_large(old_name, inv_name, 4)
                     ):
+                        logger.info(
+                            "Invitation (%s) opened by existing person (%s)."
+                            " Giving role to them and deleting invited person (%s)",
+                            invitation_link.invitation.id,
+                            old_person.id,
+                            inv_person.id,
+                        )
                         # The name is close and the invited person has not completed
                         # registration. Give the role to the existing person, and
                         # delete the invited one.
@@ -632,6 +639,15 @@ class GregOIDCBackend(ValidatingOIDCBackend):
                     else:
                         # The logged in user has gotten someone else's invitation, and
                         # the invitation should be disabled.
+                        logger.warning(
+                            "Illegal person accessed invitation (%s). Invitation belongs to"
+                            " person id %s, but was access by person id %s. Expiring"
+                            " InvitationLink %s.",
+                            invitation_link.invitation.id,
+                            inv_person.id,
+                            old_person.id,
+                            invitation_link.id,
+                        )
                         invitation_link.expire = timezone.now()
                         invitation_link.save()
                 else: