Use more appropriate Git commands
Use more appropriate Git commands

Update git.rb to use commands which are a better match for the goals
that git.rb is trying to achieve (ie. "git rev-parse --short" swapped in
for "git show --pretty=format", "git diff --quiet" swapped in for "git
status").

Signed-off-by: Wincent Colaiuta <c76ac2e9cd86441713c7dfae92c451f3e6d17fdc@wincent.com>

wincent/buildtools,wincent/buildtools,wincent/buildtools