Comment 1 for bug 1267494

For migration to 5.6 cluster, we can assume that all 5.5 nodes will be upgraded first to use Galera replication 3.*, so that all nodes in the new cluster will run same Galera plugin version.

When testing such 5.5 -> 5.6 scenario, it turned out that parallel applying could hit a unresolvable conflict. But, after merging the fix for: https://bugs.launchpad.net/codership-mysql/+bug/1262887 , 5.5 -> 5.6 replication can run with several slave appliers in 5.6 node.
ATM, I see no issues with replication in this direction, will run more complex load still to verify.