Merge pull request #1548 from puppetlabs/pdksync_(MAINT)_Pin_puppetlabs-puppet_agent

pdksync - (CONT-768) Pin puppetlabs-puppet_agent

Author: chelnak

.fixtures.yml

@@ -3,7 +3,9 @@ fixtures:
     "stdlib": "https://github.com/puppetlabs/puppetlabs-stdlib"
     "cron_core": "https://github.com/puppetlabs/puppetlabs-cron_core.git"
     "facts": "https://github.com/puppetlabs/puppetlabs-facts.git"
-    "puppet_agent": "https://github.com/puppetlabs/puppetlabs-puppet_agent.git"
     "provision": "https://github.com/puppetlabs/provision.git"
+    puppet_agent:
+      repo: 'https://github.com/puppetlabs/puppetlabs-puppet_agent.git'
+      ref: v4.12.1
   symlinks:
     "mysql": "#{source_dir}"