It's really hard with maven to know if your build is working or not. I've been hit several times already by buillds working fine locally and on the CIs but failing for a newcomer trying to build that project. The reason is that remote repos are not immutable and artifacts can disappear or be modified in there.
It would be nice if continnuum could help notice when this happen. A way to implement this would to be to configure Continuum to clean its local repo every N days.