PyUtils: Don't sort branches in diff_root.
Sorting the branches in the order defined by RootFileDumper takes a considerable amount of time. However, the branch ordering is irrelevant for diff_root. Disable the sorting in that case.
Sorting the branches in the order defined by RootFileDumper takes a considerable amount of time. However, the branch ordering is irrelevant for diff_root. Disable the sorting in that case.