git.origin -> git.github_pr_destination fails when specifying a SHA-1 `ref` on the origin

I’m attempting to write a macro for a workflow which will take a public Git SoT (git.origin is necessary, since this can be sources other than github or gerrit). I’d like to submit this import as a PR to a private github destination (via git.github_pr_destination).

The workflow that gets generated is pretty simple:

    core.workflow(
        name = "some_foo_name",
        mode = "SQUASH",
        origin = git.origin(
            url = url,
            ref = "someCommitHash",
        ),
        destination = git.github_pr_destination(
            url = private_url,
            destination_ref = "master",
            pr_branch = "import/some_foo_name/${CONTEXT_REFERENCE}",
        ),
        <snip...>

However, when running this workflow, I get a error stating that I need to specify the pr_branch for this:

ERROR: git.github_pr_destination is incompatible with the current origin. Origin has to be able to provide the contextReference or use '--github-destination-pr-branch' flag

Am I going about this incorrectly? What is a more idiomatic way to do this?

[sudoforge]

Actually, after reading your comment, I think there may be a slight miscommunication. I’m attempting to specify a SHA-1 for a git.origin, not a git.github_pr_origin.

[hsudhof]

Let me see about gazelle, this is something that might fit into a module; at the very least we would be open to accepting a contribution for gazelle support.