Apparently Apple's `git --version` provides different output than
Linux's. Improve the version parsing by splitting on all whitespace and
taking the exact element that should be the version out of that rather
than relying on the version we want being a suffix of the command
output.
Story: 2010002
Change-Id: I40356ee81b98c1210de348e51335a20be48bec1d
b39c812e01