message: Use Python 3 by default in Travis builds
diff: @@ -32,7 +32,7 @@ matrix:
  - os: linux
  dist: xenial
  compiler: gcc
  - env: MATRIX_EVAL="CC=gcc-6 && CXX=g++-6"
  + env: MATRIX_EVAL="CC=gcc-6 && CXX=g++-6 && PY=2"
  addons:
  apt:
  sources: ubuntu-toolchain-r-test
  @@ -40,7 +40,7 @@ matrix:
  - os: linux
  dist: xenial
  compiler: gcc
  - env: MATRIX_EVAL="CC=gcc-9 && CXX=g++-9 && PY=3"
  + env: MATRIX_EVAL="CC=gcc-9 && CXX=g++-9"
  addons:
  apt:
  sources: ubuntu-toolchain-r-test
  @@ -48,13 +48,13 @@ matrix:
  - os: linux
  dist: bionic
  compiler: clang
  - env: MATRIX_EVAL="CC=clang-9 && CXX=clang++-9 && PY=3"
  + env: MATRIX_EVAL="CC=clang-9 && CXX=clang++-9"
  addons:
  apt:
  packages: [*packages_base, clang-9]
  before_install:
  - - export PY=2
  + - export PY=3
  - eval "${MATRIX_EVAL}"
  script:
  