Manual cherry pick of core's `0a4912e`
Manual cherry pick of core's `0a4912e`

Original message: [tests] timeout integration tests on travis after 20
minutes

Bitcoin-com/BUcash,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Bitcoin-com/BUcash,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Bitcoin-com/BUcash,Bitcoin-com/BUcash,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Bitcoin-com/BUcash,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Bitcoin-com/BUcash