First subversion polls after upgrading to 1.321 fail

Having upgraded this morning to 1.321, the logs on the master (I have a master /
two slave setup) were full of:

http://hudson.pastebin.com/m33e0ce7a

until I kicked a build off manually, now the errors have stopped (presumably the
server contains no changes so there is no need to parse the changelog).

I've just committed some code and the errors are back (SCM poll rate is * * * *

• so they error once / minute). Re-Saving the config for my changed project
  makes no difference (as suggested by redsolo on IRC)