[FIX] bin/workflow: 'stack' variable was not initialized when sql query returned an empty set.

bzr revid: olt@tinyerp.com-20090817093301-epwojuey9j15ih3d

bin/workflow/instance.py

@@ -44,6 +44,7 @@ def delete(cr, ident):
 
 def validate(cr, inst_id, ident, signal, force_running=False):
     cr.execute("select * from wkf_workitem where inst_id=%s", (inst_id,))
+    stack = []
     for witem in cr.dictfetchall():
         stack = []
         workitem.process(cr, witem, ident, signal, force_running, stack=stack)