Allow Pull Request Owner to approve their own Pull Request

The use case I'm imagining is as follows:
My goal is to have 2 additional people look at my code before merging it. I am accomplishing this by requiring 2 approvals in order to merge a PR.

1. I create a PR and add Joffrey and Tyrion as reviewers:
2. Tyrion raises an issue
3. Joffrey decides to implement the issue himself, and pushes changes to the branch to be merged
4. Tyrion approves the Pull Request
5. Joffrey approves the Pull Request and merges

In this case, only 2 sets of eyes were really reviewing the code (rather than 3, as intended). I would like to configure this repo to require 3 approvals (2 independent and myself), to enforce that there are always at least 2 other people looking at the code, other than the originator - however I can't do this because Stash doesn't allow me to approve my own pull requests. It would be nice to have this option available.