Comment 1 for bug 1588336

Perhaps this can be more generally phrased as variable support, as I imagine having something beyond just the version be rather useful. For example, what if you want to use `112.0.0ubuntu1` (or similar) as your version instead of just the straight upstream version? In that case having `112.0.0` in another variable that can be used by both the version and source keys would be useful.