I've noticed that at least on our project it happens pretty often that a build
is triggered for no reason - i.e. there are no changes in the log. My guess is
this may be due to delayed messages from the CVS server - i.e. changes are
already taken care of in one of the previous job by the time a message from the
CVS server is received by Hudson.
I think it would be very useful if Hudson would be able to ignore a job
triggered automatically by a CVS notification if it finds out there are no real
CVS changes (there should be no new build and no subsequent jobs should be started).