Fix usage of `self.json.append` in `rbt patch`.
Review Request #15156 — Created July 7, 2026 and updated — Latest diff uploaded
When there were conflicts,
rbt patchcalledself.json.append()
without first callingself.json.add(..., []). This caused a
KeyError. This change fixes that up.
Applied a patch that had some conflicts and saw that things didn't
crash.