Gossip pullStore test fixes

1) Saw some sporadic failures of timeout in people's build jobs.
I think 10s sometimes doesn't cut it in CI.
Increased to 20s. If I'll see more failures after that I'll look deeper.

2) The assertions in TestHandleMessage might run twice before the test is finished
and the second time they shouldn't be tested (because replication has been finished).
Added a check for that.

Change-Id: I319106dafad242063857acab2d502a6a14689324
Signed-off-by: Yacov Manevich <yacovm@il.ibm.com>

gossip/gossip/pull/pullstore_test.go

@@ -31,7 +31,7 @@ import (
 )
 
 var pullInterval time.Duration
-var timeoutInterval = 10 * time.Second
+var timeoutInterval = 20 * time.Second
 
 func init() {
 	pullInterval = time.Duration(500) * time.Millisecond
@@ -222,11 +222,17 @@ func TestHandleMessage(t *testing.T) {
 	inst1ReceivedResponse := int32(0)
 
 	inst1.mediator.RegisterMsgHook(DigestMsgType, func(itemIds []string, _ []*proto.GossipMessage, _ comm.ReceivedMessage) {
+		if atomic.LoadInt32(&inst1ReceivedDigest) == int32(1) {
+			return
+		}
 		atomic.StoreInt32(&inst1ReceivedDigest, int32(1))
 		assert.True(t, len(itemIds) == 3)
 	})
 
 	inst1.mediator.RegisterMsgHook(ResponseMsgType, func(_ []string, items []*proto.GossipMessage, _ comm.ReceivedMessage) {
+		if atomic.LoadInt32(&inst1ReceivedResponse) == int32(1) {
+			return
+		}
 		atomic.StoreInt32(&inst1ReceivedResponse, int32(1))
 		assert.True(t, len(items) == 3)
 	})