A pull request moving the SDK passed its check against the old SDK and then failed
everywhere once it rolled out. In a merge check the test now reads the clone's history
at the tree's own go.mod pin, and holds the captured copy to the clone byte for byte.
A check clones mesh-sdk beside the controller at the commit go.mod pins; elsewhere
the test reads a copy captured at that commit, held to go.mod. A missing clone fails
instead of skipping.
Every required header set, each value in the pinned shape, and the subject
derived the same way. Read from the sdk's conformance directory by sibling
path, never copied.