I've noticed on more than one occasion that Ivy cache has staled Common SNAPSHOT jar files. In some cases I've seen more than a month old files. In fact, some very bad problems weren't tested at all, because changes in Common weren't pulled into, say, HDFS where the tests had to be executed.
I've noticed the same problem with MapReduce just today: latest cached snapshot of Common was a week old.
One can run clean ivy cache to make sure that latest versions are pulled down. However, it's inconvenient and undesirable to do every time.