If no `--local` option is passed to git config command line tool, it will relies
on the local repository and then to the user configuration ($HOME/.gitconfig).
In case the user has - for some reason - a svn repository configured in this
user configuration, the checking: `git config --get-regexp ^svn-remote\.` will
accuse that there is svn repo and so the `git cl tool`. This patch just add
the option `--local` to the git config command line tool, avoiding this
situation.

R=maruel@chromium.org,dpranke@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/13884014

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@193987 0039d316-1c4b-4281-b951-d872f2087c98