$NetBSD$

Fix http://code.google.com/p/boto/issues/detail?id=310

--- boto/ec2/blockdevicemapping.py.orig	2009-12-16 18:21:40.000000000 +0200
+++ boto/ec2/blockdevicemapping.py
@@ -75,7 +75,7 @@ class BlockDeviceMapping(dict):
     def build_list_params(self, params, prefix=''):
         i = 1
         for dev_name in self:
-            pre = '%sBlockDeviceMapping.%d' % (pre, i)
+            pre = '%sBlockDeviceMapping.%d' % (prefix, i)
             params['%s.DeviceName' % pre] = dev_name
             ebs = self[dev_name]
             if ebs.snapshot_id:
