[JENKINS-13669] willemv advocates simply failing the polling operation if possiblyCachedRepo is null.
Merge pull request #34 from willemv/master

[FIXED JENKINS-3907] Let all runs of a matrix build update to the same Mercurial revision
[FIXED JENKINS-17353] Assume UTF-8 encoding for metadata in changelog.xml.
Java 5 compatibility.
Merge branch 'master' of github.com:jenkinsci/mercurial-plugin
Backporting multiple-scms-plugin #1231be7 to solve testChangelogInMultiSCM failures.
Relinking is not necessary when using the share extension. Even more, when you relink to between shared repositories, mercurial hangs.