Test Robot PR Merge Conflicts when Rolling Back

[aebid]

Today Valeria noticed some issue with the cms-flaf-bot and specifying PRs

In tests on this PR #165 bbWW was failing the build stage when specifying Corrections_PR76.
This was due to bbWW having already commited to using Corrections_PR77 (merged and updated submodule commit sha).
The crash was then due to a merge conflict of Corrections going from PR77 back to PR76 here https://gitlab.cern.ch/cms-flaf/flaf_integration/-/pipelines/12895581

This seems to be due to the robot first checking out main (for bbWW PR77) then trying to patch the specific PR on top (for bbWW rolling back to PR76). It seems this is a vulnerability of any 'rollback' PR for the robot to test.

[kandrosov]

This is an intended behaviour. Any rollback PRs should maintain proper commit history wrt main.