Update vendor distribution

Distribution client change for class in resource

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
(cherry picked from commit d1f5e0f7a6)
Signed-off-by: Victor Vieux <vieux@docker.com>

vendor.conf

@@ -44,7 +44,7 @@ github.com/boltdb/bolt fff57c100f4dea1905678da7e90d92429dff2904
 github.com/miekg/dns 75e6e86cc601825c5dbcd4e0c209eab180997cd7
 
 # get graph and distribution packages
-github.com/docker/distribution d22e09a6686c32be8c17b684b639da4b90efe320
+github.com/docker/distribution a6bf3dd064f15598166bca2d66a9962a9555139e
 github.com/vbatts/tar-split v0.10.1
 
 # get go-zfs packages

vendor/github.com/docker/distribution/registry/client/auth/session.go

@@ -147,13 +147,18 @@ type Scope interface {
 // to a repository.
 type RepositoryScope struct {
 	Repository string
+	Class      string
 	Actions    []string
 }
 
 // String returns the string representation of the repository
 // using the scope grammar
 func (rs RepositoryScope) String() string {
-	return fmt.Sprintf("repository:%s:%s", rs.Repository, strings.Join(rs.Actions, ","))
+	repoType := "repository"
+	if rs.Class != "" {
+		repoType = fmt.Sprintf("%s(%s)", repoType, rs.Class)
+	}
+	return fmt.Sprintf("%s:%s:%s", repoType, rs.Repository, strings.Join(rs.Actions, ","))
 }
 
 // RegistryScope represents a token scope for access