message: get latest bitcoind from bluematt's PPA
diff: BLOCKSTACK_BRANCH="rc-0.14.2"
  +# get bitcoind
  +sudo add-apt-repository ppa:bitcoin/bitcoin || exit 1
  +sudo apt-get update || exit 1
  +sudo apt-get install bitcoin || exit 1
  +
  # needed on CircleCI's VMs
  pip install --upgrade pip
  pip install --upgrade six
  @@ -20,9 +25,6 @@ cd /tmp/blockstack-core/integration_tests && ./setup.py build && ./setup.py inst
  npm install -g babel
  npm install -g browserify
  -# get bitcoind
  -sudo apt-get install bitcoind || exit 1
  -
  # run the relevant integration tests
  blockstack-test-scenario blockstack_integration_tests.scenarios.name_preorder_register_portal_auth || exit 1
  blockstack-test-scenario blockstack_integration_tests.scenarios.name_preorder_register_portal_datastore || exit 1
  