Thanks a lot for sharing this action!

I am trying to use it in a workflow to make a PR to a different repo. Specifically, I am trying to set up a workflow to make a PR to update a submodule in a different repo whenever the submodule target repo is changed.

The repo where the action is running is pangeo-gallery/example-gallery (the target of the submodule), while the repo where the submodule lives is pangeo-gallery/pangeo-gallery

I am getting this error:

warning: no common commits
From https://github.com/pangeo-gallery/example-gallery
 * [new branch]      binderbot-built -> binderbot-built
 * [new branch]      github-actions  -> github-actions
 + 84b9a01...bfc1e8d master          -> master  (forced update)
 * [new branch]      binderbot-built -> origin/binderbot-built
 * [new branch]      github-actions  -> origin/github-actions
 + 84b9a01...bfc1e8d master          -> origin/master  (forced update)
hub pull-request   -b master   -h binderbot-update   --no-edit   -m "Update pangeo-gallery/example-gallery submodule" -m ":crown: *An automated PR*"   || true
Error creating pull request: Unprocessable Entity (HTTP 422)
Invalid value for "head"

It looks like the action is trying to make the PR from pangeo-gallery/example-gallery, rather than pangeo-gallery/pangeo-gallery. I would like it to come from pangeo-gallery/pangeo-gallery, which I have already checked out earlier in my workflow.

Is this possible?

My workflow is here:
https://github.com/pangeo-gallery/example-gallery/blob/master/.github/workflows/pangeo-gallery.yaml

You can see the log here:
https://github.com/pangeo-gallery/example-gallery/runs/515467109?check_suite_focus=true#step:6:11