Whenever a checkin is made on a branch that is unrelated to the current build
job, that job will trigger a build anyway, even though none of the job's HEAD
revisions have changed. This is a reversion in behaviour between build 312 and
321.

For example, say I have two branches: trunk and branches/bugfix. I make a change
and check it in on branches/bugfix. My hudson job is set up to checkout trunk,
and to poll every ten minutes to see if a build is necessary. It sees the
repository revision change because of the checkin on branches/bugfix and starts
building from trunk.

I expect it to ignore the fact that branches/bugfix has changed. The trunk HEAD
revision shouldn't be changed by a checkin to branches/bugfix, so the SCM
trigger shouldn't fire.

Subversion repository version is 1.6.3.