Allow navigation to Create a new Merge request with a known source branch and an unknown target branch
- Backend weight: 1
- Frontend weight: 2
Problem to solve
Right now, if you navigate to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/new?merge_request[source_branch]=master, where master is the repository default branch you get an error message. We need it to take you to the compare versions page where you could select any target branch - probably with the target branch not selected at all.
This is UX debt resulting from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28665.
Intended users
Web IDE
Further details
From the Web IDE - sometimes we want to be able to create a merge request from master to an unknown branch
Proposal
When the source_branch value is the repository default branch and the target_branch param is not present, don't prefill the target_branch with the repository default branch. Instead, show the existing placeholder in the target_branch list.