fix: restore missing blob file when re-publishing a package (#39239)

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/packages/content_store.go

@@ -4,11 +4,14 @@
 package packages
 
 import (
+	"errors"
 	"io"
+	"io/fs"
 	"net/url"
 	"path"
 	"strings"
 
+	"gitea.dev/modules/optional"
 	"gitea.dev/modules/setting"
 	"gitea.dev/modules/storage"
 	"gitea.dev/modules/util"
@@ -40,11 +43,15 @@ func (s *ContentStore) GetServeDirectURL(key BlobHash256Key, filename, method st
 	return s.store.ServeDirectURL(KeyToRelativePath(key), filename, method, reqParams)
 }
 
-// FIXME: Workaround to be removed in v1.20
-// https://github.com/go-gitea/gitea/issues/19586
-func (s *ContentStore) Has(key BlobHash256Key) error {
-	_, err := s.store.Stat(KeyToRelativePath(key))
-	return err
+func (s *ContentStore) OptionalSize(key BlobHash256Key) (sz optional.Option[int64], _ error) {
+	st, err := s.store.Stat(KeyToRelativePath(key))
+	if errors.Is(err, fs.ErrNotExist) {
+		return sz, nil
+	}
+	if err != nil {
+		return sz, err
+	}
+	return optional.Some(st.Size()), nil
 }
 
 // Save stores a package blob