Snapshot download can fail because of uint256 overflow

[chfast]

INFO  12-11 22:29:12 p2p  snap   Requested chunk #7ac6e805… from ##0b6de411…
INFO  12-11 22:29:15 p2p  snap   Requested chunk #37a1874a… from ##0b6de411…
INFO  12-11 22:29:27 p2p  net    Active peer count: 24
INFO  12-11 22:29:27 p2p  net    Looking for peers...
INFO  12-11 22:29:29 p2p  snap   Requested chunk #122d183b… from ##0b6de411…
INFO  12-11 22:29:57 p2p  net    Active peer count: 22
INFO  12-11 22:29:57 p2p  net    Looking for peers...
INFO  12-11 22:30:22 p2p  snap   Requested chunk #2be875ce… from ##90ac12ff…
INFO  12-11 22:30:24 p2p  snap   Saved chunk #2be875ce… Chunks left: 2307 (peer: ##90ac12ff…)
INFO  12-11 22:30:24 p2p  snap   Requested chunk #bf6c31c4… from ##90ac12ff…
INFO  12-11 22:30:24 p2p  snap   Requested chunk #f6151dff… from ##a7419ceb…
INFO  12-11 22:30:25 p2p  snap   Saved chunk #f6151dff… Chunks left: 2306 (peer: ##a7419ceb…)
INFO  12-11 22:30:25 p2p  snap   Requested chunk #a949805f… from ##a7419ceb…
INFO  12-11 22:30:26 p2p  snap   Saved chunk #a949805f… Chunks left: 2305 (peer: ##a7419ceb…)
INFO  12-11 22:30:26 p2p  snap   Requested chunk #6b08a7f1… from ##a7419ceb…
INFO  12-11 22:30:26 p2p  snap   Saved chunk #6b08a7f1… Chunks left: 2304 (peer: ##a7419ceb…)
INFO  12-11 22:30:26 p2p  snap   Requested chunk #95df1bd2… from ##a7419ceb…
INFO  12-11 22:30:27 p2p  net    Active peer count: 26
INFO  12-11 22:30:27 p2p  net    Looking for peers...
INFO  12-11 22:30:28 p2p  snap   Requested chunk #c329cf68… from ##90ac12ff…
INFO  12-11 22:30:28 p2p  snap   Saved chunk #95df1bd2… Chunks left: 2302 (peer: ##a7419ceb…)
INFO  12-11 22:30:28 p2p  snap   Requested chunk #c28345fb… from ##a7419ceb…
INFO  12-11 22:30:28 p2p  snap   Requested chunk #c786543a… from ##a7419ceb…
INFO  12-11 22:30:29 p2p  snap   Saved chunk #c786543a… Chunks left: 2301 (peer: ##a7419ceb…)
INFO  12-11 22:30:29 p2p  snap   Requested chunk #66c5e3c1… from ##a7419ceb…
INFO  12-11 22:30:29 p2p  snap   Saved chunk #66c5e3c1… Chunks left: 2300 (peer: ##a7419ceb…)
INFO  12-11 22:30:29 p2p  snap   Requested chunk #d58e6b83… from ##a7419ceb…
INFO  12-11 22:30:30 p2p  snap   Saved chunk #c329cf68… Chunks left: 2299 (peer: ##90ac12ff…)
INFO  12-11 22:30:30 p2p  snap   Requested chunk #c09549ff… from ##90ac12ff…
INFO  12-11 22:30:30 p2p  snap   Saved chunk #d58e6b83… Chunks left: 2299 (peer: ##a7419ceb…)
INFO  12-11 22:30:30 p2p  snap   Requested chunk #ce54ac4c… from ##a7419ceb…
terminate called after throwing an instance of 'boost::wrapexcept<dev::BadCast>'
  what():  /home/builder/project/libdevcore/RLP.h(259): Throw in function _T dev::RLP::toInt(int) const [_T = boost::multiprecision::number<boost::multiprecision::backends::cpp_int_backend<256, 256, boost::multiprecision::unsigned_magnitude, boost::multiprecision::unchecked, void>, boost::multiprecision::et_off>]
Dynamic exception type: boost::wrapexcept<dev::BadCast>