Hi Glenn,
Thanks for posting! Your change suggestion makes sense and I'll look into ways in which I can do this, though I'm curious about the issue you're experiencing with this tag and I'm wondering if you can tell me a bit more about your working situation. It doesn't seem normal to me that you should need to commit projects with a failing build into source control.
The PreviouslyBuiltSuccessfully setting is used to control a message that is shown to help people fix builds that have never passed before. Is it possible that these builds would pass on your teammate's machines but not on your own? In theory, once the property has been set once it should never change again.
Cheers,
Remco