LDAP users with uppercase usernames cannot add favourites

LDAP users with uppercase usernames cannot add favorites after upgrading to Confluence v3.1. The error message is similar to:

You are not permitted to add the label(s) ~admin@admin.com:favourite to this page.

Could replicate on MySQL with both case sensitive and in-sensitive collation.
The external_entities table stores the usernames correctly preserving the case.

Lower case LDAP usernames do not experience this problem. Cannot be replicated with local users.

No errors logged into the log files. This is not related to the upgrade task as it can be replicated in a brand new 3.1 instance.