It seems p2p-compactblocks.py fails randomly

From: https://travis-ci.org/bitcoin/bitcoin/jobs/163788152 from #8841
The PR is trivial and totally unrelated to compact block

```
p2p-compactblocks.py:
Initializing test directory /tmp/test3yd_2q3h/2
start_node: bitcoind started, waiting for RPC to come up
start_node: RPC succesfully started
MiniNode: Connecting to Bitcoin Node IP # 127.0.0.1:11016
Testing SENDCMPCT p2p message... 
Testing compactblock headers and shortIDs are correct...
Assertion failed: 
Stopping nodes
Not cleaning up dir /tmp/test3yd_2q3h/2
Failed
stderr:
  File "/home/travis/build/bitcoin/bitcoin/qa/rpc-tests/test_framework/test_framework.py", line 151, in main
    self.run_test()
  File "/home/travis/build/bitcoin/bitcoin/build/../qa/rpc-tests/p2p-compactblocks.py", line 614, in run_test
    self.test_compactblock_construction()
  File "/home/travis/build/bitcoin/bitcoin/build/../qa/rpc-tests/p2p-compactblocks.py", line 264, in test_compactblock_construction
    assert(self.test_node.last_cmpctblock is not None)
Pass: False, Duration: 7 s
```

if (!nodestate->fSupportsDesiredCmpctVersion) {
        
        return;
    }
    if (nodestate->fProvidesHeaderAndIDs) {
        for (std::list<NodeId>::iterator it = lNodesAnnouncingHeaderAndIDs.begin(); it != lNodesAnnouncingHeaderAndIDs.end(); it++) {
            if (*it == pfrom->GetId()) {
                lNodesAnnouncingHeaderAndIDs.erase(it);
                lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
                return;
            }
        }
        bool fAnnounceUsingCMPCTBLOCK = false;
        uint64_t nCMPCTBLOCKVersion = (pfrom->GetLocalServices() & NODE_WITNESS) ? 2 : 1;
        if (lNodesAnnouncingHeaderAndIDs.size() >= 3) {
            
            
            bool found = connman.ForNode(lNodesAnnouncingHeaderAndIDs.front(), [fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion](CNode* pnodeStop){
                pnodeStop->PushMessage(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion);
                return true;
            });
            if(found)
                lNodesAnnouncingHeaderAndIDs.pop_front();
        }
        fAnnounceUsingCMPCTBLOCK = true;
        pfrom->PushMessage(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion);
        lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
    }
}
bool CanDirectFetch(const Consensus::Params &consensusParams)