added more wait for green status on aggs tests

src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramTests.java

@@ -807,7 +807,7 @@ public class DateHistogramTests extends ElasticsearchIntegrationTest {
 
     @Test
     public void unmapped() throws Exception {
-        client().admin().cluster().prepareHealth("idx_unmapped").setWaitForYellowStatus().execute().actionGet();
+        client().admin().cluster().prepareHealth("idx_unmapped").setWaitForGreenStatus().execute().actionGet();
 
         SearchResponse response = client().prepareSearch("idx_unmapped")
                 .addAggregation(dateHistogram("histo").field("date").interval(DateHistogram.Interval.MONTH))