The branch checkout landed after the rsync, where git checkout --force reverts
the tree to the branch's committed state and discards everything rsync had just
written. The export then found no changes and published nothing, while still
printing a bundle path and looking like it had worked. A silent no-op is the
worst shape for this: the next person believes the export ran.
Scope: product
(cherry picked from commit 06c584240e)
442db6a664