Description of problem:
Drafting bug per https://url.corp.redhat.com/b289d64
Online cluster's login UI shows text "You can use your existing ... Red Hat Customer Portal, or other Red Hat account to log in", and shows input box with placeholder "Email address or other Red Hat Login ID"

But If the email was first registered on the openshift cluster as account xxxx and then is also used to fill in form when reigistering on the customer portal with another name yyyy (called RH Login ID), login with the yyyy will fail with prompt message "Invalid login or password". This message is not only unhelpful, but also confusing

Version-Release number of selected component (if applicable):
E.g. free-stg:
OpenShift Master:
    v3.6.173.0.5 (online version 3.5.0.20)
Kubernetes Master:
    v1.6.1+5115d708d7 

How reproducible:
Always

Steps to Reproduce:
1. Given company email xxxx WAS FIRST registered in cluster
2. And given yyyy is LATER registered in Customer Portal access.redhat.com with company email filled during the registering and yyyy is activated via confirmation link
3. Open cluster https://console.free-stg.openshift.com --> click "LOGIN WITH RED HAT" in the redirected page
4. Input yyyy and password to login
5. Again, in Customer Portal, update yyyy's email to another new email
Then try login to cluster

Actual results:
2. Registered in Customer Portal successfully
4. The login UI shows text "Customer Portal" and "Red Hat Login ID" as in above "Description".
But login failed with message "Invalid login or password". This is unhelpful and very confusing
5. Now yyyy can login

Expected results:
4. Two possible results. Either the login succeeds, or, it fails but points correct cause

Additional info: