Bug in the repo path for the binder

[brian-rose]

This line in the build-book.yaml workflow assumes that a PR originates from

--repo ${{ github.actor }}/$CI_REPOSITORY_NAME

and send this as input to binderbot when we need to point to the current PR branch to build a new image on the binder (because of a change in the environment file).

But this logic assumes that the PR branch is always in ${{ github.actor }}'s personal GitHub space. If someone who is a member of the ProjectPythia org opens a PR from a branch owned by the organization, it fails.

The reason it fails is because ${{ github.actor }} points to that person's user name, but the repo name is actually ProjectPythia/$CI_REPOSITORY_NAME.

An example is ProjectPythia/na-cordex-viz-cookbook#7.

Note that when you edit a file directly on GitHub it defaults to creating a new branch within the org, which is what happened in the above example.

[brian-rose]

In ProjectPythia/na-cordex-viz-cookbook#13 we found another version of this same failure. The PR branch is https://github.com/bonnland/na-cordex-viz-cookbook/tree/fix-environment, but when I closed and reopened the PR just to trigger a rebuild, the build failed because the Binder was looking for the code under my user-name:

It shouldn't matter who clicks the "reopen" button! The Binder should always be pointed toward the PR branch.