Merge Request Target should be the parent branch, not the default branch

Description

When creating a Merge Request from the "MR" link on the project page, the target branch is always set to the default branch of the project. Often, this is not the right choice.

In our workflow, developers want to merge into the parent branch from which they created their feature/bugfix branch. Because that is what they based their work on, that's what they have rebased against, etc.

It not just inconvenient to have to change the target branch, for us it leads to many incorrect Merge Requests.

Proposal

Make the parent branch of the developer's branch the initial target branch in the "New Merge Request" page.

In simple workflows, nobody will notice the difference. In more complex workflows, especially involving multi-level integration strategies and maintenance branches, it would be very helpful.