Cherry pick v1.7 into master

vendor/github.com/kolo/xmlrpc/response.go

@@ -0,0 +1,52 @@
+package xmlrpc
+
+import (
+	"regexp"
+)
+
+var (
+	faultRx = regexp.MustCompile(`<fault>(\s|\S)+</fault>`)
+)
+
+type failedResponse struct {
+	Code  int    `xmlrpc:"faultCode"`
+	Error string `xmlrpc:"faultString"`
+}
+
+func (r *failedResponse) err() error {
+	return &xmlrpcError{
+		code: r.Code,
+		err:  r.Error,
+	}
+}
+
+type Response struct {
+	data []byte
+}
+
+func NewResponse(data []byte) *Response {
+	return &Response{
+		data: data,
+	}
+}
+
+func (r *Response) Failed() bool {
+	return faultRx.Match(r.data)
+}
+
+func (r *Response) Err() error {
+	failedResp := new(failedResponse)
+	if err := unmarshal(r.data, failedResp); err != nil {
+		return err
+	}
+
+	return failedResp.err()
+}
+
+func (r *Response) Unmarshal(v interface{}) error {
+	if err := unmarshal(r.data, v); err != nil {
+		return err
+	}
+
+	return nil
+}