get_manifest_refs was using the btree root in its stale copy of the
super block. It is supposed to use the btree root that it was given by
its caller who went to the trouble of finding a sufficiently current
btree root.
Signed-off-by: Mark Fasheh <mfasheh@versity.com>
[zab: added commit message and fixed formatting]
Signed-off-by: Zach Brown <zab@versity.com>