[mmwatch] TypeError: cannot use a string pattern on a bytes-like object

[jijianwen]

When running mmwatch with python3, got the error as below:

python3 mmwatch 'iptables -L -v -n -x | head'
mmwatch:35: FutureWarning: split() requires a non-empty pattern match.
  p = digits_re.split(out)
Traceback (most recent call last):
  File "mmwatch", line 71, in <module>
    main(sys.argv[1:])
  File "mmwatch", line 35, in main
    p = digits_re.split(out)
TypeError: cannot use a string pattern on a bytes-like object