no-op commit to note that the example given in the previous commit is

no-op commit to note that the example given in the previous commit is
a very bad one, since the shift does not actually overflow.  This is
a better example (assuming uint64_t = unsigned long long):

  ~0LLU >> 9             =   0x7fffffffffffffLLU
  ~0LLU >> 9 << 10       = 0xfffffffffffffc00LLU
  ~0LLU >> 9 << 10 >> 10 =   0x3fffffffffffffLLU