Pin python-pymysql latest version MOS repo.

Change-Id: Ia42b38284331484df7bafe80773b7f5e1b28fd01
diff --git a/neutron/control/cluster.yml b/neutron/control/cluster.yml
index dd1d3ee..9beed6b 100644
--- a/neutron/control/cluster.yml
+++ b/neutron/control/cluster.yml
@@ -4,6 +4,12 @@
 - service.neutron.control.cluster
 - system.haproxy.proxy.listen.openstack.neutron
 parameters:
+  linux:
+    system:
+      package:
+        python-pymysql:
+          fromrepo: ${_param:openstack_version}
+          version: latest
   mysql:
     server:
       database: