Changes that are made in SVN (possible other SCMs as well) AFTER start of the build but BEFORE end of BuildWrapper.preCheckout are not checked out.

I created a BuildWrapper implementation that waits until several mirrored svn repositories are at the same revision. When the repos are in synch I want the SCM client in Jenkins to checkout the (then current) HEAD revision. Much to my surprise, the HEAD revision at the start of the build is checked out instead.

Reproduction scenario:
Configure a job with the attached SleepBuildWrapper.
Trigger a new build.
Within 20 seconds, commit a change to a svn repo attached to the job.
Wait until the checkout is done.

• Note that the revision you just committed is not in the checkout.