don't log a versioning conflict failure, even in DEBUG level

modules/elasticsearch/src/main/java/org/elasticsearch/action/support/replication/TransportShardReplicationOperationAction.java

@@ -423,9 +423,11 @@ public abstract class TransportShardReplicationOperationAction<Request extends S
                     retry(fromDiscoveryListener, shard.shardId());
                     return;
                 }
+                if (!(e instanceof VersionConflictEngineException)) {
                     if (logger.isDebugEnabled()) {
                         logger.debug(shard.shortSummary() + ": Failed to execute [" + request + "]", e);
                     }
+                }
                 listener.onFailure(e);
             }
         }