New Helm magic to delete a previous values file key

cmd/helm/install.go

@@ -273,6 +273,14 @@ func (i *installCmd) run() error {
 // Merges source and destination map, preferring values from the source map
 func mergeValues(dest map[string]interface{}, src map[string]interface{}) map[string]interface{} {
 	for k, v := range src {
+		// If the new value is literally the string "null", remove the value's key.
+		// This allows helm's multiple value sources (value files or --set) to
+		// remove incompatible keys from the previous values.
+		if v == "null" {
+			delete(dest, k)
+			continue
+		}
+
 		// If the key doesn't exist already, then just set the key to that value
 		if _, exists := dest[k]; !exists {
 			dest[k] = v