Bulk change Date fields with Relative date instead of Absolute date

Currently, when bulk editing issues, users can only set an absolute, fixed date for Date fields.

There're times when several issues have different due dates and need to be delayed equally by one month, for example, but this cannot be done by Bulk Edit: the issues will have the same due date which is not expected.

It's great if this kind of field can accept such values as "+ 30d" or "- 1w".