Pin Bazel to 0.28.1 because of a remote execution bug. (#809)
Pin Bazel to 0.28.1 because of a remote execution bug. (#809)

We can roll-forward to 0.29.1 when it is released.

bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration