Switch to go mod

vendor/github.com/heroku/docker-registry-client/registry/errortransport.go

@@ -0,0 +1,44 @@
+package registry
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+)
+
+type HttpStatusError struct {
+	Response *http.Response
+	Body     []byte // Copied from `Response.Body` to avoid problems with unclosed bodies later. Nobody calls `err.Response.Body.Close()`, ever.
+}
+
+func (err *HttpStatusError) Error() string {
+	return fmt.Sprintf("http: non-successful response (status=%v body=%q)", err.Response.StatusCode, err.Body)
+}
+
+var _ error = &HttpStatusError{}
+
+type ErrorTransport struct {
+	Transport http.RoundTripper
+}
+
+func (t *ErrorTransport) RoundTrip(request *http.Request) (*http.Response, error) {
+	resp, err := t.Transport.RoundTrip(request)
+	if err != nil {
+		return resp, err
+	}
+
+	if resp.StatusCode >= 400 {
+		defer resp.Body.Close()
+		body, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return nil, fmt.Errorf("http: failed to read response body (status=%v, err=%q)", resp.StatusCode, err)
+		}
+
+		return nil, &HttpStatusError{
+			Response: resp,
+			Body:     body,
+		}
+	}
+
+	return resp, err
+}