restore the ordering of nested modules

In order for depends_on to work, modules need to implicitly depend on
their child modules. This will have little effect on terraform's
concurrency, as configuration trees are always much wider than they are
deep.

terraform/transform_module_expansion.go

@@ -60,6 +60,16 @@ func (t *ModuleExpansionTransformer) Transform(g *Graph) error {
 		}
 	}
 
+	// Modules implicitly depend on their child modules, so connect closers to
+	// other which contain their path.
+	for _, c := range t.closers {
+		for _, d := range t.closers {
+			if len(d.Addr) > len(c.Addr) && c.Addr.Equal(d.Addr[:len(c.Addr)]) {
+				g.Connect(dag.BasicEdge(c, d))
+			}
+		}
+	}
+
 	return nil
 }