When a user gets renamed locally to a new name, under which no global account exists and no conflicts accounts exists, the global account should be created automatically.
Maybe this can also be checked on user login, than other (or the previous renamed) user accounts without a conflict can also benefit from this. Should be part of a automigration (wgCentralAuthAutoMigrate).
Version: unspecified
Severity: enhancement
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=14862