Make sure latch is always counted down

Author: slandelle

client/src/test/java/org/asynchttpclient/channel/ConnectionPoolTest.java

@@ -89,7 +89,7 @@ public void testMaxTotalConnectionsException() throws Throwable {
         }
     }
 
-    @Test(groups = "standalone", invocationCount = 10)
+    @Test(groups = "standalone", invocationCount = 100)
     public void asyncDoGetKeepAliveHandlerTest_channelClosedDoesNotFail() throws Exception {
 
         try (AsyncHttpClient client = asyncHttpClient()) {
@@ -111,6 +111,15 @@ public Response onCompleted(Response response) throws Exception {
                     }
                     return response;
                 }
+
+                @Override
+                public void onThrowable(Throwable t) {
+                    try {
+                        super.onThrowable(t);
+                    } finally {
+                        l.countDown();
+                    }
+                }
             };
 
             client.prepareGet(getTargetUrl()).execute(handler).get();