Automated g4 rollback of changelist 50265868.

*** Reason for rollback ***

Multibound set is no longer Serializable, whoops.

*** Original change description ***

Give more information when duplicate elements are found in a multibound set.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=50268399
2 files changed