Follow-up from hiding the rebase button for FF trains
requested to merge 433136-follow-up-from-do-not-require-mrs-to-be-rebased-when-using-ff-merge-trains-2 into master
What does this MR do and why?
Increases coverage of the should_be_rebased? method in core as a follow-up.
Handles the case where there is no car pipeline the car is active and the train_ref commit_sha is not present.
Further context here: #433136 (comment 1713164944)
Related to #433136 (closed)
Edited by Allison Browne