* (
bug 23126) CentralAuth: restore original behavior where 'locked' global accounts cannot be used to log in or merge, *unless* $wgCentralAuthLockedCanEdit is non-empty, in which case we allow them through so their edits can be filtered by that whitelist.
This avoids polluting logs and user namespaces with merges unless the feature for allowing locked accounts to edit certain request pages has been explicitly enabled. (It does not appear to be enabled on any Wikimedia sites at the moment, but if it were it would probably be on Meta.)