A new Galera feature that allows retrying of applying of writesets at
slave nodes (codership/mysql-wsrep-bugs/#1619). Currently replication
applying stops for first non ignored failure occurring in event
applying, and node will do emergency abort (or start inconsistency
voting). Some failures, however, can be concurrency related, and
applying may succeed if the operation is tried at later time.

This feature introduces a new dynamic global option variable
wsrep_applier_retry_count that controls the retry-applying feature:
a zero value disables retrying and a positive value sets the maximum
number of retry attempts. The default value for this option is zero,
which means that this feature is disabled by default.