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The Mercurial Distributed Version Control System comes as standard with an extension providing some integration with Bugzilla bug tracking.
The Mercurial extension uses the Bugzilla XML-RPC API to interact with Bugzilla.
In 4.4.3, Bugzilla changes the way it authenticates use of the API. This breaks the Bugzilla extension distributed with Mercurial versions 3.0 and prior.
For Mercurial 3.0, this patch will get things working again.