message: Update or-tools to v6.7.2
  This fix updates or-tools from (dated 03/21/2017)
  to the latest versioned release version of v6.7.2
diff: @@ -144,13 +144,13 @@ def tf_workspace(path_prefix="", tf_repo_name=""):
  tf_http_archive(
  name = "ortools_archive",
  urls = [
  - "https://mirror.bazel.build/github.com/google/or-tools/archive/253f7955c6a1fd805408fba2e42ac6d45b312d15.tar.gz",
  + "https://mirror.bazel.build/github.com/google/or-tools/archive/v6.7.2.tar.gz",
  # Please uncomment me, when the next upgrade happens. Then
  # remove the whitelist entry in third_party/repo.bzl.
  - # "https://github.com/google/or-tools/archive/253f7955c6a1fd805408fba2e42ac6d45b312d15.tar.gz",
  + # "https://github.com/google/or-tools/archive/v6.7.2.tar.gz",
  ],
  - sha256 = "932075525642b04ac6f1b50589f1df5cd72ec2f448b721fd32234cf183f0e755",
  - strip_prefix = "or-tools-253f7955c6a1fd805408fba2e42ac6d45b312d15/src",
  + sha256 = "d025a95f78b5fc5eaa4da5f395f23d11c23cf7dbd5069f1f627f002de87b86b9",
  + strip_prefix = "or-tools-6.7.2/src",
  build_file = clean_dep("//third_party:ortools.BUILD"),
  )
  