Domas recently disabled Special:Makesysop because of some kind of
replication problem, by commenting out the inclusion of the extension.
What he didn't realise is that that extension also sets up the rights
for Wikimedia-style steward and bureaucrat groups. Thus, these groups
reverted to the MediaWiki default.
The MediaWiki default is to give the initial user (a bureaucrat), the
ability to change all user rights, using Special:Userrights. So
bureaucrats across Wikimedia were pleased to find that they had been
granted total, unrestricted access to their wikis. Though hopefully few
of them realised it, this included the right to grant themselves steward
access, and perform operations such as locking the wiki with
Special:Lockdb, or requesting user IP addresses with Special:Checkuser.
When Special:Makesysop is re-enabled, anyone still retaining developer
privileges will have full interwiki rights, such as the ability to sysop
or desysop anyone on any wiki.
Access to Special:Userrights has been disabled once more, although if
anyone was granted high-level access without proper process during this
period (developer, checkuser or boardvote), they should own up so that
it can be reverted.
-- Tim Starling