Test: testNodeNotReachableFromMaster had a typo when choosing a non master node

src/test/java/org/elasticsearch/discovery/DiscoveryWithServiceDisruptions.java

@@ -817,7 +817,7 @@ public class DiscoveryWithServiceDisruptions extends ElasticsearchIntegrationTes
         while (nonMasterNode == null) {
             nonMasterNode = randomFrom(internalCluster().getNodeNames());
             if (nonMasterNode.equals(masterNode)) {
-                masterNode = null;
+                nonMasterNode = null;
             }
         }