Fixes regression introduced with f980289

- since `where_values_hash` is a public method
- f980289 changes `where_values_hash` to return indifferent hash in 3-stable branch
- similar patch was applied to 4 branch in 5dc2e3531 but without conversion to indifferent hash
- assuming that indifferent hash is the way to go - convert result of  `where_values_hash` in 4 branch aswell