message: Try to switch dist
diff: @@ -17,7 +17,7 @@ matrix:
  include:
  - os: linux
  - dist: bionic
  + dist: xenial
  name: GCC 9
  python: 3.7
  @@ -25,6 +25,7 @@ matrix:
  apt:
  sources:
  - sourceline: 'ppa:ubuntu-toolchain-r/test'
  + - sourceline: 'ppa:deadsnakes/ppa'
  packages:
  - g++-9 python3.7
  env:
  