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 !=