DRILL-6920: Fix TestClient.testBasics() yarn test failure

closes #1582
diff --git a/drill-yarn/src/test/java/org/apache/drill/yarn/client/TestClient.java b/drill-yarn/src/test/java/org/apache/drill/yarn/client/TestClient.java
index 73f1b00..8be3148 100644
--- a/drill-yarn/src/test/java/org/apache/drill/yarn/client/TestClient.java
+++ b/drill-yarn/src/test/java/org/apache/drill/yarn/client/TestClient.java
@@ -105,6 +105,7 @@
     } catch (SimulatedExitException e) {
       assert (e.exitCode == -1);
       assertTrue(TestContext.getOut().contains("Usage: "));
+      TestContext.resetOutput();
     }
 
     // Bogus command
@@ -115,16 +116,7 @@
     } catch (SimulatedExitException e) {
       assert (e.exitCode == -1);
       assertTrue(TestContext.getOut().contains("Usage: "));
-    }
-
-    // Help command
-
-    try {
-      DrillOnYarn.run(new String[] { "help" });
-      fail();
-    } catch (SimulatedExitException e) {
-      assert (e.exitCode == -1);
-      assertTrue(TestContext.getOut().contains("Usage: "));
+      TestContext.resetOutput();
     }
   }