[travis] workaroud sudo apt-get update failures in Travis
[travis] workaroud sudo apt-get update failures in Travis

https://github.com/travis-ci/travis-ci/issues/8607

mnhrdt/s2p,dyoussef/s2p,MISS3D/s2p,MISS3D/s2p,MISS3D/s2p,carlodef/s2p,dyoussef/s2p,carlodef/s2p,dyoussef/s2p,MISS3D/s2p,dyoussef/s2p,mnhrdt/s2p