repository: Do not report ignored packs in EachByPack

Ignored packs were reported as an empty pack by EachByPack. The most
immediate effect of this is that the progress bar for rebuilding the
index reports processing more packs than actually exist.

internal/repository/index.go

@@ -276,10 +276,10 @@ func (idx *Index) EachByPack(ctx context.Context, packBlacklist restic.IDSet) <-
 			m := &idx.byType[typ]
 			m.foreach(func(e *indexEntry) bool {
 				packID := idx.packs[e.packIndex]
-				if _, ok := byPack[packID]; !ok {
-					byPack[packID] = make([][]*indexEntry, restic.NumBlobTypes)
-				}
 				if !idx.final || !packBlacklist.Has(packID) {
+					if _, ok := byPack[packID]; !ok {
+						byPack[packID] = make([][]*indexEntry, restic.NumBlobTypes)
+					}
 					byPack[packID][typ] = append(byPack[packID][typ], e)
 				}
 				return true