Merge branch 'ld/p423'

Code preparation to make "git p4" closer to be usable with Python 3.

* ld/p423:
  git-p4: python3: fix octal constants
  git-p4: python3: use print() function
  git-p4: python3: basestring workaround
  git-p4: python3: remove backticks
  git-p4: python3: replace dict.has_key(k) with "k in dict"
  git-p4: python3: replace <> with !=