Rebase option to synchronize pull request

Hey dear developers!

We would like to ask you to implement the new button, for saving time of many programmers. When we are doing Pull Request now, while it's not rebased yet to the top of the target branch, we are doing rebase manually every time and push changes again:

command for example:
git rebase master
git push ..

But better would be, if your service had such button on the website. Could you implement it? You have of course "Sync now", but it's doing some mess with merging but not a rebasing..

Please provide second more suitable option "Rebase to top of target branch" that could be applied before merging.

Hope for understanding! Thank you for attention.