It appears with the recent fixes to the subversion features that its broken
something todo with triggering builds.

What it appears to be doing is detecting that the repository revision # has
changed and starts a build. When that build finishes however, hudson doesn't
update the revision #. As a result, in the next poll of the SCM hudson builds
again. For whatever reason, on the second attempt, hudsons revision number is
correctly updated.

The result is duplicate builds for every SCM checkin using Subversion