Be conservative requiring python-yaml.

A lot of modules require python-yaml. Be conservative requiring this
package to avoid conflicts when two or more of these modules end up
being used on the same host.

Change-Id: I35bf4f1070e6f248734c593e9277b737166904c1
Reviewed-on: https://review.openstack.org/13688
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Paul Belanger <paul.belanger@polybeacon.com>
Approved: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Tested-by: Jenkins

modules/jenkins/manifests/job_builder.pp

@@ -4,8 +4,12 @@ class jenkins::job_builder (
     $password,
 ) {
 
-  package { 'python-yaml':
-    ensure => "present",
+  # A lot of things need yaml, be conservative requiring this package to avoid
+  # conflicts with other modules.
+  if ! defined(Package['python-yaml']) {
+    package { 'python-yaml':
+      ensure => "present",
+    }
   }
 
   package { "python-jenkins":

modules/zuul/manifests/init.pp

@@ -12,12 +12,20 @@ class zuul (
                "python-lockfile",
                "python-paramiko",
                "python-paste",
-               "python-yaml"]
+              ]
 
   package { $packages:
     ensure => "present",
   }
 
+  # A lot of things need yaml, be conservative requiring this package to avoid
+  # conflicts with other modules.
+  if ! defined(Package['python-yaml']) {
+    package { 'python-yaml':
+      ensure => "present",
+    }
+  }
+
   # Packages that need to be installed from pip
   $pip_packages = ["GitPython"]