map: tweak isbn

1 files changed, 3 insertions, 12 deletions

diff --git a/skate/map.go b/skate/map.go
index 17d9ed2..a6dc5f3 100644
--- a/skate/map.go
+++ b/skate/map.go
@@ -289,22 +289,13 @@ func MapperOpenLibraryReleaseNormalizedISBN(p []byte) (fields [][]byte, err erro
 	}
 	// There can be 10 and 13 variants in the data, we always want 13.
 	for _, isbn := range doc.ExtIDs.ISBN {
-		if len(isbn) == 13 {
-			isbn13 = isbn
+		parsed := ParseIsbn(isbn)
+		if len(parsed) > 0 {
+			isbn13 = parsed[0]
 			break
 		}
 	}
 	if isbn13 == "" {
-		// This is rarer, more expensive.
-		for _, isbn := range doc.ExtIDs.ISBN {
-			parsed := ParseIsbn(isbn)
-			if len(parsed) > 0 {
-				isbn13 = parsed[0]
-				break
-			}
-		}
-	}
-	if isbn13 == "" {
 		return nil, nil
 	} else {
 		key = []byte(isbn13)