> The slf4j-simple jar is no longer included.
It shouldn't be, should it? Avro 1.2 used to pull it in as a required dependency, which was a bug, and Common explicitly had to block it. Avro 1.3 only requires the slf4j API, not any of its implementations. Hadoop uses the log4j implementation of slf4j, which both common and mapreduce's ivy.xml explicitly require, but perhaps not in all the right contexts?
That error message is triggered when no slf4j implementation is on the classpath. When is this printed?