terraform: fix graph test

terraform/graph.go

@@ -440,7 +440,11 @@ func graphAddDiff(g *depgraph.Graph, d *Diff) error {
 				i--
 
 			case *GraphNodeResourceProvider:
-				// Keep these around
+				// Keep these around, but fix up the source to be ourselves
+				// rather than the old node.
+				newDep := *dep
+				newDep.Source = n
+				deps[i] = &newDep
 			default:
 				panic(fmt.Errorf("Unhandled depedency type: %#v", dep.Meta))
 			}

terraform/graph_test.go

@@ -334,7 +334,7 @@ func TestGraphAddDiff_destroy(t *testing.T) {
 	actual := strings.TrimSpace(g.String())
 	expected := strings.TrimSpace(testTerraformGraphDiffDestroyStr)
 	if actual != expected {
-		t.Fatalf("bad:\n\n%s", actual)
+		t.Fatalf("bad:\n\n%s\n\nexpected:\n\n%s", actual, expected)
 	}
 
 	// Verify that the state has been added