Bitbucket pull request creation API should have an option to set the owner

Right now we use the API here to generate pull requests automatically as part of our ci workflow: https://developer.atlassian.com/static/rest/bitbucket-server/4.10.1/bitbucket-rest.html#idp896512

This works great, but due to the way we’re set up, we have an automation user (cl_buildbot) that supplies its credentials to generate this pull request. Because of the way Bitbucket works, this means that cl_buildbot is also the owner of the pull request, even though it is creating the pull request on behalf of someone else.

This makes managing PRs a little difficult on Stash, since they’re all generated by one user.

We would rather not manually generate pull requests as this is inconvenient.

We would also really rather not have to have each submitter supply credentials to the buildbot (for authenticating via the API) as this is both very inconvenient and not so secure.

So simply allowing us to set the owner at creation time (or after the fact) would be a major improvement.