Currently the NewGit workflow sets up git submodules to point to a
.git dir through a textfile indirection. git-svn isn't smart enough to
deal with this, and so we need to change things to use symlinks instead.

In the meantime, 'fetch blink' will fail. For now, we'll turn off
the svn configuration.

TBR=iannucci@chromium.org

BUG=

Review URL: https://codereview.chromium.org/13560005

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@192230 0039d316-1c4b-4281-b951-d872f2087c98