From 785ac3ab71e896f8c03df7da36f3da51135945c7 Mon Sep 17 00:00:00 2001
From: "Paul \"TBBle\" Hampson" <Paul.Hampson@Pobox.com>
Date: Wed, 13 Jan 2021 05:44:03 +1100
Subject: [PATCH] Ensure request.header is never nil

Header.Clone() will return `nil` if called on a nil object.

Signed-off-by: Paul "TBBle" Hampson <Paul.Hampson@Pobox.com>
---
 remotes/docker/resolver.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/remotes/docker/resolver.go b/remotes/docker/resolver.go
index b062d20d3..3481c5132 100644
--- a/remotes/docker/resolver.go
+++ b/remotes/docker/resolver.go
@@ -446,6 +446,9 @@ func (r *dockerBase) filterHosts(caps HostCapabilities) (hosts []RegistryHost) {
 
 func (r *dockerBase) request(host RegistryHost, method string, ps ...string) *request {
 	header := r.header.Clone()
+	if header == nil {
+		header = http.Header{}
+	}
 
 	for key, value := range host.Header {
 		header[key] = append(header[key], value...)