Sorting by More/Less weight

Summary

If we sort using "More weight", all Issues that were setted to 0 or more weight should appear first.

Steps to reproduce

Click the combo to sort by "More weight".

What is the current bug behavior?

All Issues that there are no weight are appear first (see print screen below).

What is the expected correct behavior?

IMO, when we sort by "More weight" we should to see Issues that have weight (sorted by this number) and after, all Issues without weight.

When we sort by "Less weight" we should see all Issues without weight first and then all that have weight.

Relevant logs and/or screenshots

Sort using More weight:

Sort using Less weight:

Output of checks

This bug happens on GitLab.com