Merge branch 'ls/p4-retry-thrice'

A recent updates to "git p4" was not usable for older p4 but it
could be made to work with minimum changes.  Do so.

* ls/p4-retry-thrice:
git-p4: do not pass '-r 0' to p4 commands

diff --cc Documentation/git-p4.txt
Simple merge

diff --cc git-p4.py
Simple merge