Fix vars.

playbooks/roles/jenkins_admin/templates/edx/var/jenkins/jobs/build-ami/config.xml.j2

@@ -177,7 +177,7 @@ cd util/vpc-tools/
 echo "$refs" > /var/tmp/$BUILD_ID-refs.yml
 cat /var/tmp/$BUILD_ID-refs.yml
 
-echo "$vars" > /var/tmp/$BUILD_ID-extra-vars.yml
+echo "\$vars" > /var/tmp/$BUILD_ID-extra-vars.yml
 cat /var/tmp/$BUILD_ID-extra-vars.yml
 
 python -u abbey.py -p $play -t c1.medium  -d $deployment -e $environment -i {{jenkins_home}}/.ssh/id_rsa -b $base_ami --vars /var/tmp/$BUILD_ID-extra-vars.yml --refs /var/tmp/$BUILD_ID-refs.yml -j $release_id --mongo-uri $mongo_uri --mongo-deployment-collection $deployment --mongo-db devops --configuration-version $configuration --configuration-secure-version $configuration_secure -k {{JENKINS_ADMIN_EC2_KEY}} --configuration-secure-repo &quot;{{JENKINS_ADMIN_CONFIGURATION_SECURE_REPO}}&quot;</command>