In some enviroments (eg, OSX zh_CN), use 'svn --version' and splitting string
may get error version string. Use 'svn --version --quiet' to do stable svn
version check, which directly returns version string such as '1.7.0'.

BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10805037

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@147670 0039d316-1c4b-4281-b951-d872f2087c98