Pin python-pymysql latest version MOS repo.

Change-Id: Ia42b38284331484df7bafe80773b7f5e1b28fd01
diff --git a/nova/control/cluster.yml b/nova/control/cluster.yml
index d47c5e1..dee725d 100644
--- a/nova/control/cluster.yml
+++ b/nova/control/cluster.yml
@@ -11,6 +11,12 @@
     nova_ram_allocation_ratio: 1.5
     nova_disk_allocation_ratio: 1.0
     metadata_password: metadataPass
+  linux:
+    system:
+      package:
+        python-pymysql:
+          fromrepo: ${_param:openstack_version}
+          version: latest
   nova:
     controller:
       enabled: true