When the promoted build plugin attempts to tag a build, the following stacktrace occurs:

Started by user anonymous
Promoting test #1
moduleLocation: Remote ->http://svn/trunk/demo
Tag Base URL: 'http://svn/tags/demo-TEST'.
Delete old tag http://svn/tags/demo-TEST.
FATAL: null
java.lang.NullPointerException
at hudson.plugins.svn_tag.SvnTagPlugin.perform(SvnTagPlugin.java:226)
at hudson.plugins.svn_tag.SvnTagPublisher.perform(SvnTagPublisher.java:116)
at hudson.plugins.promoted_builds.Promotion$RunnerImpl.build(Promotion.java:124)
at hudson.plugins.promoted_builds.Promotion$RunnerImpl.doRun(Promotion.java:103)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:416)
at hudson.model.Run.run(Run.java:1198)
at hudson.plugins.promoted_builds.Promotion.run(Promotion.java:75)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:122)