Bad pagination in Issues API when issues have identical timestamps

This error occurs when a project have several issues that have identical updated_on timestamps.

The repositories/user/project/issues will include some issues in more than one page, while some issues are not included in any page.

It is probably impossible to get to this state by normal means, but by using the export/import function I created more than 40 issues with identical properties except for id and title. I did this in order to test that my tool handled the pagination correctly.

Ordering by id worked as expected, but the default ordering and sort=updated_on triggered the bug.