VSTS git pull request policy
It's better to include the pull request policy in VSTS, such as require branch be rebased.
Our scenario is for sprints, when we are complete with development of many feature branches that are merged into trunk branch and we want to merge into a test branch (that is configured for CD to deploy to an Azure environment). Many times, we get merge conflicts due to the *many* changes being merged into the test branch. We have someone manage the test environment and deployment to it, but he's not as skilled handling merge conflicts which has meant involving developers to manually resolve, but a rebase would (I think) work better for such pull requests. I agree it would make sense to have it be branch policy-based since pull requests from feature branches into trunk would not need this.
I think this can be implemented in a way that it does not inconvenience the developer. If a new "Merge requirement" is added that will first rebase and then merge to the target, in most of the cases, it will go thru without the developer having to do it manually.
Another policy I feel is missing is requiring fast-forward merges only.