I installed ikiwiki v3.14159 in /usr/local from tarball (/usr contains an older version). Having done so, and used ikiwiki-transition to update setup file, the post commit hook is now blocking in flock (as seen by ps). I should also mention that I added the goodstuff, attachment and remove plugins (which was the purpose of upgrading to v3). Any clues as how to debug/fix gratefully received. The wiki is publically viewable at wiki.sgcm.org.uk if that helps.