In 2019 Pau observed an error where an empty attributes hash was passed
to the bulk product update method. He added an automated test but wasn't
able to reproduce the error.
A recent change in logic made the spec fail but rspec-retry hid that
fail because it would succeed on a second try (not sure why). I now
changed the logic to ignore empty attributes properly and avoid an error
trying to create a new variant when no attributes are given.
* f940397781 Pau's spec
* 6f228781d4 Fixing error detection