Before the s///:

length = 14
31 2e 32 33 34 2e 35 36 37 2e 08 2c 38 39
 1  .  2  3  4  .  5  6  7  . ^H  ,  8  9

After the s///:

length = 11
31 32 33 34 35 36 37 08 2c 38 39
 1  2  3  4  5  6  7 ^H  ,  8  9