message: construction_worker: different source
diff: @@ -33,7 +33,7 @@ matrix:
  env: COMPILER=clang-3.8
  addons:
  apt:
  - sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-3.7']
  + sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.7']
  packages: ['g++-6', 'clang-3.7']
  ################
  