Rename 'ast' variable that shadowed package name.
Rename 'ast' variable that shadowed package name.

google/go-jsonnet,google/go-jsonnet,google/go-jsonnet,sbarzowski/go-jsonnet,sbarzowski/go-jsonnet,google/go-jsonnet,google/go-jsonnet,sbarzowski/go-jsonnet,sbarzowski/go-jsonnet,sbarzowski/go-jsonnet