system:admin Certs get mixed up

[wkulhanek]

This is not a really big deal since "developer" gets sudoer and can give itself cluster-admin...

But when running multiple clusters the .kube/config file gets confused with regards to what the right certificate is for system:admin. As a result after a few up and downs / creates and destroys of clusters it is no longer possible to log in as system:admin. Trying oc prompts for a password for the system:admin id.