Update assert to account for fetch phase tripping the cb

Author: andreidan

server/src/internalClusterTest/java/org/elasticsearch/action/search/TransportSearchIT.java

@@ -78,6 +78,7 @@
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertResponse;
 import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.either;
 import static org.hamcrest.Matchers.equalTo;
 
 public class TransportSearchIT extends ESIntegTestCase {
@@ -487,7 +488,10 @@ public void onFailure(Exception e) {
                     Exception.class,
                     client.prepareSearch("test").addAggregation(new TestAggregationBuilder("test"))
                 );
-                assertThat(exc.getCause().getMessage(), containsString("<reduce_aggs>"));
+                assertThat(
+                    exc.getCause().getMessage(),
+                    either(containsString("<reduce_aggs>")).or(containsString("fetch phase source loader"))
+                );
             });
 
             final AtomicArray<Exception> exceptions = new AtomicArray<>(10);
@@ -514,7 +518,10 @@ public void onFailure(Exception exc) {
             latch.await();
             assertThat(exceptions.asList().size(), equalTo(10));
             for (Exception exc : exceptions.asList()) {
-                assertThat(exc.getCause().getMessage(), containsString("<reduce_aggs>"));
+                assertThat(
+                    exc.getCause().getMessage(),
+                    either(containsString("<reduce_aggs>")).or(containsString("fetch phase source loader"))
+                );
             }
             assertBusy(() -> assertThat(requestBreakerUsed(), equalTo(0L)));
         } finally {