JIRA Login Fails With the Message - User xxxx has no unique key mapping

Steps to Reproduce (these are the steps received from customers)

1. Upgrade to JIRA 7.0
2. Attempt to login to JIRA

Expected Results

1. Login is successful

Actual Results

Login fails with the below exception:

java.lang.IllegalStateException: User 'xxxx' exists but has no unique key mapping.
at com.atlassian.jira.user.util.DefaultUserManager.getUserByName(DefaultUserManager.java:262)
at com.atlassian.jira.security.login.JiraSeraphAuthenticator.getUser(JiraSeraphAuthenticator.java:36)
at com.atlassian.seraph.auth.DefaultAuthenticator.login(DefaultAuthenticator.java:101)
at com.atlassian.seraph.filter.PasswordBasedLoginFilter.runAuthentication(PasswordBasedLoginFilter.java:127)

Workaround

Refer to our JIRA Login Fails With the Message - User exists but has no unique key mapping KB for the workaround.

Real World

Your "workaround" does not work and the issue has been closed despite a number of customers still reporting the issue. It now seems to have worked its way into Jira 7 Software. NONE of my Crowd users have been ported over, not one, so that I now cannot access the system at all.