Fix regression from 5e8d57bec1a21c39b55f20c67425c065405f8153

0 is a false value, so shortcutting no longer works.
Update other places in the code that assumed graph was the default.
Merge pull request #434 from brian-brazil/graphlink

Fix regression from 5e8d57bec1a21c39b55f20c67425c065405f8153