Pull an image named by its digest as the runtime's own client does, and say a pull that failed

replays/docker.go

@@ -75,11 +75,21 @@ func (d *Docker) Pull(ctx context.Context, image string) error {
 	if err := d.call(ctx, http.MethodGet, "/images/"+url.PathEscape(image)+"/json", nil, nil); err == nil {
 		return nil
 	}
-	name, tag, _ := strings.Cut(image, ":")
-	if tag == "" {
-		tag = "latest"
+	// A digest is the tag the runtime is asked for, as its own client asks: `name@sha256:…` cut at the
+	// `@`; otherwise the tag after the last `:` that is not part of a registry's port.
+	name, tag, digested := strings.Cut(image, "@")
+	if !digested {
+		name, tag = image, "latest"
+		if at := strings.LastIndex(image, ":"); at > strings.LastIndex(image, "/") {
+			name, tag = image[:at], image[at+1:]
+		}
 	}
-	return d.call(ctx, http.MethodPost, "/images/create?fromImage="+url.QueryEscape(name)+"&tag="+url.QueryEscape(tag), nil, nil)
+	err := d.call(ctx, http.MethodPost, "/images/create?fromImage="+url.QueryEscape(name)+"&tag="+url.QueryEscape(tag), nil, nil)
+	if err != nil {
+		return err
+	}
+	// The runtime answers a pull it could not make with a stream that ends in an error, not a status.
+	return d.call(ctx, http.MethodGet, "/images/"+url.PathEscape(image)+"/json", nil, nil)
 }
 
 // Network makes a network of its own and answers its id.