Description of problem:
will meet "API error (403)" error when pushing image with Docker credentials.

Version-Release number of selected component (if applicable):
oc v3.0.1.0-388-g51e9da7
kubernetes v1.0.0

docker version:
Client version: 1.6.2
Client API version: 1.18
Go version (client): go1.4.2
Git commit (client): ba1f6c3/1.6.2
OS/Arch (client): linux/amd64
Server version: 1.6.2
Server API version: 1.18
Go version (server): go1.4.2
Git commit (server): ba1f6c3/1.6.2
OS/Arch (server): linux/amd64

How reproducible:
always

Steps to Reproduce:
1. Setup the OpenShift V3 environment according to: OpenShift 3 Application Lifecycle Sample  and login to server
$ oc login --server=$master -u $user
$ oc new-project $project-name

2. Get the '.dockercfg' file which contain account credential
1) register an account on DockerHub
2) log in to the registry to get the account credential
$ docker login ## the credential file named ".dockercfg" will be generated under $HOME directory after login successfully

3. Create the secret
$ oc secrets new pushme path/to/.dockercfg

4. Add the secret "pushme" to builder service account
$ oc secrets add serviceaccount/builder secrets/pushme

5. Update buildconfig to relate above secret
$ oc edit buildconfig/$bc-name
     <----------snip--------->
       {
         "kind": "ImageStream",
         "apiVersion": "v1beta1",
         "metadata": {
           "name": "origin-ruby-sample"
         },
         "spec":{
         "dockerImageRepository": "chunyunchen/origin-ruby-sample"
       },
             "parameters": {
        "output": {
          "to": {
            "kind": "ImageStreamTag",
            "name": "origin-ruby-sample:latest"
          },
          "pushSecret":{
             "name":"pushme"   ## the "pushSecretName" is the same with above secret name
          }
        },
     <----------snip--------->
        "strategy": {
          "type": "Source"
        }
      },
     <----------snip--------->

6. Create the application to trigger build and wait the build to finish
$ oc process -f template.json | oc create -f -

7. Check the build logs
$ oc get build
$ oc build-logs ruby-sample-build-1

Actual results:
<---------------snip--------------->
I0722 02:13:53.788552       1 docker.go:521] Committing container with config: {Hostname: Domainname: User: Memory:0 MemorySwap:0 CPUShares:0 CPUSet: AttachStdin:false AttachStdout:false AttachStderr:false PortSpecs:[] ExposedPorts:map[] Tty:false OpenStdin:false StdinOnce:false Env:[OPENSHIFT_BUILD_NAME=ruby-sample-build-2 OPENSHIFT_BUILD_NAMESPACE=chunp OPENSHIFT_BUILD_SOURCE=https://github.com/openshift/sti-python BUILD_LOGLEVEL=5] Cmd:[/usr/local/sti/run] DNS:[] Image: Volumes:map[] VolumesFrom: WorkingDir: MacAddress: Entrypoint:[] NetworkDisabled:false SecurityOpts:[] OnBuild:[] Labels:map[io.openshift.s2i.build.image:registry.access.redhat.com/openshift3/python-33-rhel7:latest io.openshift.s2i.build.commit.author:Michal Fojtik <mi> io.openshift.s2i.build.commit.id:6755bbc io.openshift.s2i.build.commit.ref:master io.k8s.display-name:chunyunchen/python-sample-722:latest io.openshift.s2i.build.commit.date:Wed Jul 15 17:55:59 2015 +0200 io.openshift.s2i.build.commit.message:Merge pull request #46 from mfojtik/fix-build-script io.openshift.s2i.build.source-location:https://github.com/openshift/sti-python io.openshift.s2i.build.source-context-dir:3.3/test/standalone-test-app]}
I0722 02:13:56.634909       1 sti.go:269] Successfully built chunyunchen/python-sample-722:latest
I0722 02:13:57.968547       1 cleanup.go:23] Removing temporary directory /tmp/sti027940679
I0722 02:13:57.968601       1 fs.go:99] Removing directory '/tmp/sti027940679'
I0722 02:13:57.969189       1 cfg.go:78] Found Docker authentication configuration in '/root/.dockercfg'
I0722 02:13:57.969203       1 cfg.go:46] PUSH_DOCKERCFG_PATH=/var/run/secrets/openshift.io/push/.dockercfg
I0722 02:13:57.969208       1 cfg.go:78] Found Docker authentication configuration in '/var/run/secrets/openshift.io/push/.dockercfg'
I0722 02:13:57.969232       1 cfg.go:50] Problem accessing /var/run/secrets/openshift.io/push/.dockercfg: stat /var/run/secrets/openshift.io/push/.dockercfg: no such file or directory
I0722 02:13:57.969251       1 sti.go:148] Pushing chunyunchen/python-sample-722:latest image ...
E0722 02:13:57.972207       1 dockerutil.go:50] push for image chunyunchen/python-sample-722:latest failed, will retry in 10s ...
E0722 02:14:07.981425       1 dockerutil.go:50] push for image chunyunchen/python-sample-722:latest failed, will retry in 10s ...
F0722 02:14:18.678584       1 builder.go:64] Build error: Failed to push image: API error (403): Error: Status 403 trying to push repository chunyunchen/python-sample-722 to official registry: needs to be forced

Expected results:
Should push image with Docker credentials successfully.

Additional info:
the same bug on OpenShift Origin:
https://bugzilla.redhat.com/show_bug.cgi?id=1224210