Stop ErrFinishedWalk from escaping from Repositories walk

Signed-off-by: Edgar Lee <edgar.lee@docker.com>

registry/handlers/catalog.go

@@ -9,7 +9,6 @@ import (
 	"strconv"
 
 	"github.com/docker/distribution/registry/api/errcode"
-	"github.com/docker/distribution/registry/storage"
 	"github.com/docker/distribution/registry/storage/driver"
 	"github.com/gorilla/handlers"
 )
@@ -51,7 +50,7 @@ func (ch *catalogHandler) GetCatalog(w http.ResponseWriter, r *http.Request) {
 
 	if err == io.EOF || pathNotFound {
 		moreEntries = false
-	} else if err != nil && err != storage.ErrFinishedWalk {
+	} else if err != nil {
 		ch.Errors = append(ch.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
 		return
 	}

registry/storage/catalog.go

@@ -29,6 +29,10 @@ func (reg *registry) Repositories(ctx context.Context, repos []string, last stri
 		return 0, err
 	}
 
+	// errFinishedWalk signals an early exit to the walk when the current query
+	// is satisfied.
+	errFinishedWalk := errors.New("finished walk")
+
 	err = Walk(ctx, reg.blobStore.driver, root, func(fileInfo driver.FileInfo) error {
 		err := handleRepository(fileInfo, root, last, func(repoPath string) error {
 			foundRepos = append(foundRepos, repoPath)