Looks like there is a design flaw within TeamCity handling of VCS labels. To me it looks like there is an assumption that labelling of the source code is really fast, so you can report build results before you actually put a label on source code.
In our setup we have huge ClearCase deployment which is used across the globe by many teams and it is actually quite slow. So even with medium sized project it takes significant time to put a lable on all elements within VCS.
Is it possible to configure a build so it will not report success until TeamCity puts a label on all elements within VCS?