Gitlab: Option to enable Delete source branch by default in Create Merge Request and in Merge window

There is an option in Gitlab to enable Delete source branch by default for newly created merge requests.

But it gets enabled for merge requests created only in a browser.

If I create Merge request in SmartGit I always get this option disabled.

It would be great if the default setting was used when creating merge request in SmartGit and also an option to enable or disable it in Merge Merge request window.