Feature request: Commit ranges to last successful job OR last ancestor commit

[justinmakaila]

I'm currently looking into expanding the functionality of this orb to include an opt-in flag to go back to the last successful job.

This is the use case:
A developer files a PR against a branch. The job is executed to return commit A (first commit) and commit B (most recent commit). Tests are executed against the changes between commit A and commit B. The tests fail and abort (leaving some package tests un-executed). The developer makes changes to the affected tests and pushes commit C.

Currently, the orb will return the compare URL for B and C. The proposed functionality will check for the outcome on the job result from the CircleCI API, decrementing and doing another iteration in the failed, canceled, and timedout case.