Fix race condition in JedisSentinelPoolTest

The test was issuing the failover command and only afterwards
connecting to the pub-sub channel to receive failover notifications.
If the failover occurred fast enought the pub-sub listener would never
get the notification.

Run the failover command on a separate Jedis connection after we're
absolutely sure that we're subscribed to the pub-sub channel.

src/test/java/redis/clients/jedis/tests/utils/JedisSentinelTestUtil.java

@@ -8,7 +8,8 @@ import redis.clients.jedis.JedisPubSub;
 import redis.clients.jedis.tests.utils.FailoverAbortedException;
 
 public class JedisSentinelTestUtil {
-    public static HostAndPort waitForNewPromotedMaster(Jedis sentinelJedis) 
+    public static HostAndPort waitForNewPromotedMaster(final String masterName, 
+        final Jedis sentinelJedis, final Jedis commandJedis) 
 	    throws InterruptedException {
 	
 	final AtomicReference<String> newmaster = new AtomicReference<String>(
@@ -47,6 +48,7 @@ public class JedisSentinelTestUtil {
 
 	    @Override
 	    public void onPSubscribe(String pattern, int subscribedChannels) {
+        commandJedis.sentinelFailover(masterName);
 	    }
 	}, "*");