possibly fixed issue 1151

gluon/html.py

@@ -1757,7 +1757,7 @@ class INPUT(DIV):
             t = self['_type'] = 'text'
         t = t.lower()
         value = self['value']
-        if self['_value'] is None:
+        if self['_value'] is None or isinstance(self['_value'],cgi.FieldStorage):
             _value = None
         else:
             _value = str(self['_value'])