This is somewhat of a known issue with build order. I don't understand it completely, but basically you have to make sure that you have explicitly done a mvn install on apacheds before running tests, and this probably needs to be done on your machine any time you checkout a new version or sitch to a different branch that you have never built locally before. This is relevant to the core-plugin and bootstrapping the schemas.
I probably explained this incorrectly, but suffice to say that this is a known gotcha.
Sorry - I would reply to my own thread, but google hides it from me. That last message may have been just a one time corruption in server-work. It happened right after I built 1.5.1-SNAPSHOT, and updated my dependencies. I tried downgrading my dependencies, but it was still there. Then I deleted server-work, and now the tests run fine. I'll post back if I see anything suspicious :-) Have a great weekend everybody.