Add experimental-zuul-pep8-ubuntu-xenial job

In an effort to make our bindep dependencies better, we want to
experiment having the pep8 jobs not use our wheel mirrors.  This
ensures that projects are able to be build properly if our wheel
mirror is down or a new python dependency is released by has not been
build by our wheel-build job.

This is patch will be reverted once we confirmed the job works as
expected.

Change-Id: I03be650963e8f0e5630ad658882b0ce6692c4b45
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

jenkins/jobs/infra.yaml

@@ -437,3 +437,26 @@
               keep-hierarchy: true
               copy-after-failure: false
       - console-log
+
+- job:
+    name: experimental-zuul-pep8-ubuntu-xenial
+
+    builders:
+      - zuul-git-prep-upper-constraints
+      - install-distro-packages
+      - shell: |
+          #!/bin/bash -xe
+          # Write global pip configuration minus wheel mirror.
+          awk '!/extra-index-url/' /etc/pip.conf > /tmp/pip.conf
+          sudo mv /tmp/pip.conf /etc/
+          sudo chown root:root /etc/pip.conf
+          sudo chmod 0644 /etc/pip.conf
+      - revoke-sudo
+      - pep8:
+          env: pep8
+
+    publishers:
+      - test-results
+      - console-log
+
+    node: ubuntu-xenial

zuul/layout.yaml

@@ -5089,6 +5089,8 @@ projects:
     post:
       - zuul-coverage-ubuntu-trusty
       - zuul-coverage-ubuntu-xenial
+    experimental:
+      - experimental-zuul-pep8-ubuntu-xenial
     periodic:
       - periodic-test