Fix pypi jeepyb requirement collision.

Change-Id: Ib6b9413ce127434d3b0e69fd15aa314f492cb389
Reviewed-on: https://review.openstack.org/17311
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins

modules/pypimirror/manifests/init.pp

@@ -17,9 +17,11 @@ class pypimirror(
   include remove_nginx
   include jeepyb
 
+  if ! defined(Package['python-yaml']) {
     package { 'python-yaml':
       ensure => present,
     }
+  }
 
   file { '/usr/local/mirror_scripts':
     ensure => directory,