Getting a list of changed files in BitBucket Pipelines

Question

I know that I can limit specific steps to "condition: changesets: includePaths:" That's not what I'm trying to do.

I know that I can get a list of modified files in the last commit with git diff. That, unfortunately, isn't sufficient.

What I would like to do is get a list of all of the files which have been modified in this branch since last push. For instance, imagine that you do the following:

1. Create a branch.
2. Commit A.
3. Push.
4. Commit B.
5. Commit C.
6. Commit D.
7. Push.

I want a list of the files modified in all of B, C and D so that I can pass them to my testing scripts and evaluate all of the files which have been modified since the last time the pipeline was able to run.

With pull-requests, I think I can do this by diffing BITBUCKET_COMMIT and BITBUCKET_PR_DESTINATION_BRANCH. But for pipeline steps which I want to run simply any time commits are pushed, I can't figure out how to get the changeset I want.