Fix gclient-new-workdir.py

Was broken by the refactor done in
http://crrev.com/900a33fb4df00cf36c87f4c5c11b4390b23e2a03

BUG=

Review URL: https://codereview.chromium.org/1462553002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@297633 0039d316-1c4b-4281-b951-d872f2087c98

gclient-new-workdir.py

@@ -75,8 +75,7 @@ def main():
       print('Creating: %s' % workdir)
       git_common.make_workdir(os.path.join(root, '.git'),
                               os.path.join(workdir, '.git'))
-      subprocess.check_call(['git', 'checkout', '-f'],
+      subprocess.check_call(['git', 'checkout', '-f'], cwd=workdir)
-                            cwd=new_workdir.rstrip('.git'))
 
 
 if __name__ == '__main__':