Conformance test issue -- GET request to blob URL from prior request should yield 200

[wy65701436]

This issue is a sub-task of the OCI Conformance testing epic (#11943)

~~~ REQUEST ~~~
GET  /v2/conformance/testrepo/blobs/sha256:66ad98165d38f53ee73868f82bd4eed60556ddfee824810a4062c4f777b20a5b  HTTP/1.1
HOST   : ******
HEADERS:
	Authorization: Bearer *****
	User-Agent: distribution-spec-conformance-tests
BODY   :
***** NO CONTENT *****
------------------------------------------------------------------------------
~~~ RESPONSE ~~~
STATUS       : 404 Not Found
RECEIVED AT  : 2020-05-15T06:41:38.782842659Z
TIME DURATION: 11.767813ms
HEADERS      :
	Connection: keep-alive
	Content-Length: 157
	Content-Type: application/json; charset=utf-8
	Date: Fri, 15 May 2020 06:41:38 GMT
	Docker-Distribution-Api-Version: registry/2.0
	Server: nginx
	Set-Cookie: sid=be58b79125609de248efa5255ad4d2aa; Path=/; HttpOnly
	X-Request-Id: 1da21289-6ebd-4e34-ba71-db443529234e
BODY         :
{
   "errors": [
      {
         "code": "BLOB_UNKNOWN",
         "message": "blob unknown to registry",
         "detail": "sha256:66ad98165d38f53ee73868f82bd4eed60556ddfee824810a4062c4f777b20a5b"
      }
   ]
}

Expected
: 404
to equal
: 200

[reasonerjt]

This is due to failure by #11946

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.