username discrepancy between ldap, sso and git result in "not participating" error

Hello,

We have collaborator 13.6.13601 enterprise, and recently a few users that have a specific prefix in their username in ldap, are not assigned a role on a review, instead they get "not participating", see screenshot.

in ldap the user is `t_foo`, where "t_" denotes a contractor/temporary employee

If we go into the user admin section and rename the user to "t-foo" to match what Github uses, the old "t_foo" user is recreated in Collaborator automatically, and the user still cannot be assigned to a review properly.

Most of our users have the username convention "<lastname><f>"