Background for cert-manager/cert-manager#9116. The PR moves the "next private
key does not match CSR public key" check above the failure handling in
issuing.(*controller).ProcessItem. A fair question on the PR was: the comment
above that block already says "If public key does not match, do nothing
(requestmanager will handle this)" — so how did we ever reach a state where the
controller does do something (fails the issuance) on a key mismatch?
Short answer: the check was never a gate in front of the failure branch. It