Description of problem:
Created an imagestream that only has spec.Tags,and imported image from the imagestream.But got "error: unexpected error, from is empty". 
But in fact in my imagestream,there is
 "from": {
                    "kind": "DockerImage",
                    "name": "wsun/python-33-centos"
                },

Version-Release number of selected component (if applicable):
# oc version
oc v1.1.4-16-gb5da002
kubernetes v1.2.0-origin-41-g91d3e75

How reproducible:
Always

Steps to Reproduce:
1.Create an imagestream that only has spec.Tags
# cat is.json 
{

    "kind": "ImageStream",
    "apiVersion": "v1",
    "metadata": {
      "name": "python",
      "creationTimestamp": null
    },
    "spec": {
           "tags":[
                      { "name": "3.3",
                         "annotations":
                              { "description": "wsun tests" },
                          "from":
                           {
                               "kind": "DockerImage",
                                "name": "wsun/python-33-centos"
                           }

                        }
             ]
       }

}

2.import image from imagestream
3.

Actual results:
2.]# oc import-image python --loglevel=8
I0317 03:35:53.893931    8130 loader.go:242] Config loaded from file /root/.kube/config
I0317 03:35:53.894342    8130 round_trippers.go:264] GET https://localhost:8443/api
I0317 03:35:53.894350    8130 round_trippers.go:271] Request Headers:
I0317 03:35:53.894354    8130 round_trippers.go:274]     Accept: application/json, */*
I0317 03:35:53.894359    8130 round_trippers.go:274]     Authorization: Bearer Tk8WgBz4iRN_tAUCtQGDt3KK8V8OXydpOFlELu3n4lc
I0317 03:35:53.912614    8130 round_trippers.go:289] Response Status: 200 OK in 18 milliseconds
I0317 03:35:53.912628    8130 round_trippers.go:292] Response Headers:
I0317 03:35:53.912634    8130 round_trippers.go:295]     Cache-Control: no-store
I0317 03:35:53.912639    8130 round_trippers.go:295]     Content-Type: application/json
I0317 03:35:53.912643    8130 round_trippers.go:295]     Date: Thu, 17 Mar 2016 07:35:53 GMT
I0317 03:35:53.912648    8130 round_trippers.go:295]     Content-Length: 69
I0317 03:35:53.912683    8130 request.go:875] Response Body: {"kind":"APIVersions","apiVersion":"v1","versions":["v1","v1beta3"]}
I0317 03:35:53.912868    8130 round_trippers.go:264] GET https://localhost:8443/apis
I0317 03:35:53.912875    8130 round_trippers.go:271] Request Headers:
I0317 03:35:53.912880    8130 round_trippers.go:274]     Accept: application/json, */*
I0317 03:35:53.912884    8130 round_trippers.go:274]     Authorization: Bearer Tk8WgBz4iRN_tAUCtQGDt3KK8V8OXydpOFlELu3n4lc
I0317 03:35:53.913891    8130 round_trippers.go:289] Response Status: 200 OK in 0 milliseconds
I0317 03:35:53.913904    8130 round_trippers.go:292] Response Headers:
I0317 03:35:53.913909    8130 round_trippers.go:295]     Cache-Control: no-store
I0317 03:35:53.913913    8130 round_trippers.go:295]     Content-Type: application/json
I0317 03:35:53.913918    8130 round_trippers.go:295]     Date: Thu, 17 Mar 2016 07:35:53 GMT
I0317 03:35:53.913922    8130 round_trippers.go:295]     Content-Length: 223
I0317 03:35:53.913937    8130 request.go:875] Response Body: {"kind":"APIGroupList","apiVersion":"v1","groups":[{"name":"extensions","versions":[{"groupVersion":"extensions/v1beta1","version":"v1beta1"}],"preferredVersion":{"groupVersion":"extensions/v1beta1","version":"v1beta1"}}]}
I0317 03:35:53.914383    8130 round_trippers.go:264] GET https://localhost:8443/oapi
I0317 03:35:53.914394    8130 round_trippers.go:271] Request Headers:
I0317 03:35:53.914399    8130 round_trippers.go:274]     Accept: application/json, */*
I0317 03:35:53.914403    8130 round_trippers.go:274]     User-Agent: oc/v1.1.4 (linux/amd64) openshift/b5da002
I0317 03:35:53.914407    8130 round_trippers.go:274]     Authorization: Bearer Tk8WgBz4iRN_tAUCtQGDt3KK8V8OXydpOFlELu3n4lc
I0317 03:35:53.915345    8130 round_trippers.go:289] Response Status: 200 OK in 0 milliseconds
I0317 03:35:53.915357    8130 round_trippers.go:292] Response Headers:
I0317 03:35:53.915363    8130 round_trippers.go:295]     Cache-Control: no-store
I0317 03:35:53.915367    8130 round_trippers.go:295]     Content-Type: application/json
I0317 03:35:53.915372    8130 round_trippers.go:295]     Date: Thu, 17 Mar 2016 07:35:53 GMT
I0317 03:35:53.915376    8130 round_trippers.go:295]     Content-Length: 59
I0317 03:35:53.915391    8130 request.go:875] Response Body: {"kind":"APIVersions","apiVersion":"v1","versions":["v1"]}
I0317 03:35:53.915558    8130 round_trippers.go:264] GET https://localhost:8443/oapi/v1/namespaces/wsun/imagestreams/python
I0317 03:35:53.915565    8130 round_trippers.go:271] Request Headers:
I0317 03:35:53.915569    8130 round_trippers.go:274]     Accept: application/json, */*
I0317 03:35:53.915573    8130 round_trippers.go:274]     User-Agent: oc/v1.1.4 (linux/amd64) openshift/b5da002
I0317 03:35:53.915577    8130 round_trippers.go:274]     Authorization: Bearer Tk8WgBz4iRN_tAUCtQGDt3KK8V8OXydpOFlELu3n4lc
I0317 03:35:53.917320    8130 round_trippers.go:289] Response Status: 200 OK in 1 milliseconds
I0317 03:35:53.917333    8130 round_trippers.go:292] Response Headers:
I0317 03:35:53.917338    8130 round_trippers.go:295]     Cache-Control: no-store
I0317 03:35:53.917343    8130 round_trippers.go:295]     Content-Type: application/json
I0317 03:35:53.917347    8130 round_trippers.go:295]     Date: Thu, 17 Mar 2016 07:35:53 GMT
I0317 03:35:53.917351    8130 round_trippers.go:295]     Content-Length: 876
I0317 03:35:53.917375    8130 request.go:875] Response Body: {"kind":"ImageStream","apiVersion":"v1","metadata":{"name":"python","namespace":"wsun","selfLink":"/oapi/v1/namespaces/wsun/imagestreams/python","uid":"5cfbac74-ec0e-11e5-8e84-0e057fb684c9","resourceVersion":"372","generation":2,"creationTimestamp":"2016-03-17T07:03:33Z","annotations":{"openshift.io/image.dockerRepositoryCheck":"2016-03-17T07:03:34Z"}},"spec":{"tags":[{"name":"3.3","annotations":{"description":"wsun tests"},"from":{"kind":"DockerImage","name":"wsun/python-33-centos"},"generation":2,"importPolicy":{}}]},"status":{"dockerImageRepository":"172.30.3.20:5000/wsun/python","tags":[{"tag":"3.3","items":[{"created":"2016-03-17T07:03:34Z","dockerImageReference":"wsun/python-33-centos@sha256:354d212f9a8c776a221487f4223211103f2e0c4d42ea97eeae6091523acff3ef","image":"sha256:354d212f9a8c776a221487f4223211103f2e0c4d42ea97eeae6091523acff3ef","generation":2}]}]}}
F0317 03:35:53.917849    8130 helpers.go:107] error: unexpected error, from is empty


Expected results:
Could import image successfully

Additional info:
If I use --from=wsun/python-33-centos , then I could import image successfully.And after that,even if I don't use --from any more,import-image command still work.