jenkinsci/mercurial-plugin — pull request #22 by nimeacuerdo (2012-02-19 16:05:55+00:00)
Title: JENKINS-12829: A failed update sets revision of build to 000000+

The mercurial plugin ensures that a failed clone operation throws the
corresponding exception, but that's not the case if the subsequent
update fails: no check is done of the return code of the hg update
command.

The effect is that the revision of the build is set to 000000+, which
causes a huge change log calculation in the next build, as basically
the calculated log includes all thechange setss in the history of the
repo.