Do not update if user assign to existing MR

Proposal

When autoupdater creates MR in some project other developers may interacts with it. For now autoupdater checks if last MR is made by it and if yes and there are new updates it updates it again. But it will do that in case when user make some changes and amend them to autoupdater commit. Then commit do not change owner so it will reset developer changes.

It could be a good idea to also check if someone is assign to existing MR and if yes then autoupdater aborts changes in that project.