Description of problem:


Version-Release number of selected component (if applicable):
openshift-0.5.2.2-0.git.26.701be15.el7ose.x86_64

How reproducible:
Always

Steps to Reproduce:
1.Create app from repo:
# osc new-app https://github.com/openshift/simple-openshift-sinatra-sti.git
2. Edit bc to add http_proxy var
# osc edit bc
<--snip-->
  strategy:
    sourceStrategy:
      env:
      - name: HTTPS_PROXY
        value: <---my-proxy-url--->
      from:
        kind: DockerImage
        name: openshift/ruby-20-centos7
    type: Source
<--snip-->
3. Start build
osc start-build simple-openshift-sinatra-sti
4. Check build log
osc build-logs simple-openshift-sinatra-sti-1
5. Trigger another build
6. Check build log again.

Actual results:
In step 4, I could see https_proxy is exported in build env.
I0609 06:25:27.811274       1 cfg.go:50] Problem accessing /root/.dockercfg: stat /root/.dockercfg: no such file or directory
I0609 06:25:27.812348       1 sti.go:67] Creating a new S2I builder with build request: api.Request{BaseImage:"openshift/ruby-20-centos7", DockerConfig:(*api.DockerConfig)(0xc20803b200), DockerCfgPath:"", PullAuthentication:docker.AuthConfiguration{Username:"", Password:"", Email:"", ServerAddress:""}, PreserveWorkingDir:false, Source:"https://github.com/openshift/simple-openshift-sinatra-sti.git", Ref:"", Tag:"172.30.16.32:5000/jialiu/simple-openshift-sinatra-sti:latest", Incremental:false, RemovePreviousImage:false, Environment:map[string]string{"OPENSHIFT_BUILD_NAME":"simple-openshift-sinatra-sti-5", "OPENSHIFT_BUILD_NAMESPACE":"jialiu", "OPENSHIFT_BUILD_SOURCE":"https://github.com/openshift/simple-openshift-sinatra-sti.git", "HTTPS_PROXY":"<---my-proxy-url--->"}, CallbackURL:"", ScriptsURL:"", Location:"", ForcePull:false, WorkingDir:"", LayeredBuild:false, InstallDestination:"", Quiet:false, ContextDir:""}


In step 6, "HTTPS_PROXY" var is seen in build log, but it does not take any effect, because download gem failed. 
0609 06:41:46.318695       1 docker.go:294] Creating container using config: {Hostname: Domainname: User: Memory:0 MemorySwap:0 CPUShares:0 CPUSet: AttachStdin:false AttachStdout:true AttachStderr:false PortSpecs:[] ExposedPorts:map[] Tty:false OpenStdin:true StdinOnce:true Env:[OPENSHIFT_BUILD_NAME=simple-openshift-sinatra-sti-6 OPENSHIFT_BUILD_NAMESPACE=jialiu OPENSHIFT_BUILD_SOURCE=https://github.com/openshift/simple-openshift-sinatra-sti.git HTTPS_PROXY=<---my-proxy-url--->] Cmd:[/bin/sh -c tar -C /tmp -xf - && /usr/local/sti/assemble] DNS:[] Image:openshift/ruby-20-centos7 Volumes:map[] VolumesFrom: WorkingDir: MacAddress: Entrypoint:[] NetworkDisabled:false SecurityOpts:[] OnBuild:[] Labels:map[]}
I0609 06:41:47.439405       1 docker.go:301] Attaching to container
I0609 06:41:47.444655       1 docker.go:354] Starting container
I0609 06:41:47.643346       1 docker.go:364] Waiting for container
I0609 06:41:48.025155       1 sti.go:392] ---> Installing application source
I0609 06:41:48.040129       1 sti.go:392] ---> Building your Ruby application from source
I0609 06:41:48.040175       1 sti.go:392] ---> Running 'bundle install --deployment'
I0609 06:41:54.056380       1 sti.go:392] Fetching gem metadata from https://rubygems.org/..........
I0609 06:41:59.174467       1 sti.go:392] 
I0609 06:41:59.174511       1 sti.go:392] Gem::RemoteFetcher::FetchError: Errno::ECONNRESET: Connection reset by peer - SSL_connect (https://rubygems.org/gems/rack-1.5.2.gem)
I0609 06:41:59.190462       1 sti.go:392] An error occurred while installing rack (1.5.2), and Bundler cannot continue.
I0609 06:41:59.190516       1 sti.go:392] Make sure that `gem install rack -v '1.5.2'` succeeds before bundling.
I0609 06:41:59.571938       1 docker.go:370] Container exited
I0609 06:42:01.577714       1 cleanup.go:24] Removing temporary directory /tmp/sti069837988
I0609 06:42:01.577760       1 fs.go:99] Removing directory '/tmp/sti069837988'
F0609 06:42:01.586675       1 builder.go:75] Build error: non-zero (13) exit code from openshift/ruby-20-centos7

After step 6, if I change HTTPS_PROXY to another proxy, it take effect again.

Expected results:
user's proxy setting should always take effect.

Additional info:
In my network, it is not allowed to connect outside network directly, have to use proxy, if you do have such specific network, I think you could set a invalid proxy to reprocue this issue. That means, after you set an invalid proxy, gem install would fail for the 1st time, but would succeed for the 2nd time.