Fix #1739 (opds download with anonymous browsing enabled) -> download rights of guest user are now respected again

cps/opds.py

@@ -387,8 +387,8 @@ def opds_download_link(book_id, book_format):
     # I gave up with this: With enabled ldap login, the user doesn't get logged in, therefore it's always guest
     # workaround, loading the user from the request and checking it's download rights here
     # in case of anonymous browsing user is None
-    user = load_user_from_request(request)
-    if not user or not user.role_download():
+    user = load_user_from_request(request) or current_user
+    if not user.role_download():
         return abort(403)
     if "Kobo" in request.headers.get('User-Agent'):
         client = "kobo"