Fix subchart values not being deleted by setting value to nil in parent chart's values

Signed-off-by: Stefan Deitmer <stefan.deitmer@gec.io>

pkg/chartutil/testdata/moby/charts/spouter/values.yaml

@@ -1 +1,2 @@
 scope: spouter
+foo: bar

pkg/chartutil/testdata/moby/values.yaml

@@ -22,3 +22,7 @@ web:
     httpGet:
       path: /api/v1/info
       port: atc
+
+# for testing deleting default values in sub charts
+spouter:
+  foo: null

pkg/chartutil/values.go

@@ -170,10 +170,7 @@ func CoalesceValues(chrt *chart.Chart, vals *chart.Config) (Values, error) {
 		if err != nil {
 			return cvals, err
 		}
-		cvals, err = coalesce(chrt, evals)
-		if err != nil {
-			return cvals, err
-		}
+		return coalesce(chrt, evals)
 	}
 
 	return coalesceDeps(chrt, cvals)

pkg/chartutil/values_test.go

@@ -475,6 +475,33 @@ func TestCoalesceTables(t *testing.T) {
 		t.Errorf("Expected boat string, got %v", dst["boat"])
 	}
 }
+
+func TestCoalesceSubchart(t *testing.T) {
+	tchart := "testdata/moby"
+	c, err := LoadDir(tchart)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tvals := &chart.Config{}
+
+	v, err := CoalesceValues(c, tvals)
+	if err != nil {
+		t.Fatal(err)
+	}
+	j, _ := json.MarshalIndent(v, "", "  ")
+	t.Logf("Coalesced Values: %s", string(j))
+
+	subchartValues, ok := v["spouter"].(map[string]interface{})
+	if !ok {
+		t.Errorf("Subchart values not found")
+	}
+
+	if _, ok := subchartValues["foo"]; ok {
+		t.Errorf("Expected key foo to be removed, still present")
+	}
+}
+
 func TestPathValue(t *testing.T) {
 	doc := `
 title: "Moby Dick"