Reported here https://github.com/bitcoin/bitcoin/pull/12629#issuecomment-381095603 by @Empact.  I've seen it now in a few different travis jobs, including:

https://travis-ci.org/bitcoin/bitcoin/jobs/366157920
https://travis-ci.org/bitcoin/bitcoin/jobs/366139851

From my initial investigation it seems like there may be an actual bug in block announcement, so I'm  opening this issue to track.
{
    if (!tx.IsCoinBase())
    {
        if (pvChecks)
            pvChecks->reserve(tx.vin.size());
        
        
        
        
        
        
        
        
        if (fScriptChecks) {