Vendor after merging in mtrmac/image:docker-lookaside

vendor/github.com/docker/distribution/reference/reference.go

@@ -24,6 +24,7 @@ package reference
 import (
 	"errors"
 	"fmt"
+	"strings"
 
 	"github.com/docker/distribution/digest"
 )
@@ -43,6 +44,9 @@ var (
 	// ErrDigestInvalidFormat represents an error while trying to parse a string as a tag.
 	ErrDigestInvalidFormat = errors.New("invalid digest format")
 
+	// ErrNameContainsUppercase is returned for invalid repository names that contain uppercase characters.
+	ErrNameContainsUppercase = errors.New("repository name must be lowercase")
+
 	// ErrNameEmpty is returned for empty, invalid repository names.
 	ErrNameEmpty = errors.New("repository name must have at least one component")
 
@@ -149,7 +153,9 @@ func Parse(s string) (Reference, error) {
 		if s == "" {
 			return nil, ErrNameEmpty
 		}
-		// TODO(dmcgowan): Provide more specific and helpful error
+		if ReferenceRegexp.FindStringSubmatch(strings.ToLower(s)) != nil {
+			return nil, ErrNameContainsUppercase
+		}
 		return nil, ErrReferenceInvalidFormat
 	}