osd: fix unneeded get_object_context() (and leak) in _rollback_to
osd: fix unneeded get_object_context() (and leak) in _rollback_to

All we want is the name of the head sobject_t, which is 'soid' in the
parent frame.

Signed-off-by: Sage Weil <6dd34506bbd5e58221bbb3e4732d97c91f02277b@newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph