If a tar were constructed with duplicate file names, then depending on
the order, it could result in same tarsum.
Signed-off-by: Vincent Batts <vbatts@redhat.com>
this is to enhance the tarsum algorithm, but _MUST_ be done in lock step
with the same for docker-registry. (PR will be cited)
Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)