stop sync if an invalid block was received
stop sync if an invalid block was received

ethereum/pyethapp,gsalgado/pyethapp,changwu-tw/pyethapp,danielnovy/test,heikoheiko/pyethapp,ethereum/pyethapp,kustomzone/pyethapp,vaporry/pyethapp,changwu-tw/pyethapp,gsalgado/pyethapp,RomanZacharia/pyethapp,d-das/pyethapp,RomanZacharia/pyethapp