Emulate running gclient from a checkout containing .gclient and a DEPS, with the
solution having an url set to None.

TEST=new smoke test

Review URL: http://codereview.chromium.org/2897010

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@52119 0039d316-1c4b-4281-b951-d872f2087c98