Fix bug regarding node UUID in haskell node queries

When moving from python to haskell node queries, a bug
was discovered where a node's UUID was mistakenly
compared to a node's name. This indirectly caused the
cluster epo operation to fail, because it was not
able to identify the master node.
Signed-off-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Hrvoje Ribicic <riba@google.com>

src/Ganeti/Query/Node.hs

@@ -200,7 +200,7 @@ nodeFields =
      FieldSimple (rsNormal . nodeSecondaryIp), QffNormal)
   , (FieldDefinition "master" "IsMaster" QFTBool "Whether node is master",
      FieldConfig (\cfg node ->
-                    rsNormal (nodeName node ==
+                    rsNormal (nodeUuid node ==
                               clusterMasterNode (configCluster cfg))),
      QffNormal)
   , (FieldDefinition "group" "Group" QFTText "Node group",