[src] Small fix in test code, avoid spurious failure (#2978)

src/nnet3/nnet-compile-utils-test.cc

@@ -95,7 +95,7 @@ void UnitTestSplitLocationsBackward(bool verbose) {
  num_locations : max_generated_submat_list_size;
  submat_lists[i].reserve(num_locations);
  for (int32 j = 0; j < num_locations; j++) {
- if (j <= min_num_kaddrows)
+ if (j <= min_num_kaddrows && j < num_submat_indexes)
  // since we need min_num_kaddrows in the split_lists we ensure that
  // we add a pair with the same first element in all the submat_lists
  submat_lists[i].push_back(std::make_pair(submat_indexes[j],