Offline deployment: PyPi repo (#3542)

roles/bootstrap-os/tasks/bootstrap-coreos.yml

@@ -60,6 +60,7 @@
 - name: Install required python modules
   pip:
     name: "{{ item }}"
+    extra_args: "{{ pip_extra_args | default(omit) }}"
   with_items: "{{pip_python_coreos_modules}}"
   environment:
     PATH: "{{ ansible_env.PATH }}:{{ bin_dir }}"