in clear() clear journal tables as well.

Match clear in back_anydbm.

Author: rouilj

roundup/backends/rdbms_common.py

@@ -967,6 +967,8 @@ def clear(self):
         for cn in self.classes:
             sql = 'delete from _%s' % cn
             self.sql(sql)
+            sql = 'delete from %s__journal' % cn
+            self.sql(sql)
 
     #
     # Nodes