message: Remove redundant initialization of collective params.
  subdiv_permutations is being resized twice in GenerateSubdivParams.
diff: @@ -318,9 +318,6 @@ void SortDevicesAndTasks(CollectiveParams* cp) {
  // ring order implicit in the device order.
  void GenerateSubdivPerms(const string& device, int source_rank,
  CollectiveParams* cp) {
  - CHECK_GT(cp->instance.impl_details.subdiv_offsets.size(), 0);
  - cp->instance.impl_details.subdiv_permutations.resize(
  - cp->instance.impl_details.subdiv_offsets.size());
  // Each subdiv permutation is a ring formed by rotating each
  // single-task subsequence of devices by an offset. This makes most
  // sense when each task has the same number of devices but we can't
  