Comment 5 for bug 913819

Not sure if it is the correct way to handle this but the following change in linaro-image-tools (rev 485) worked for me.

$ bzr diff
=== modified file 'linaro_image_tools/media_create/boards.py'
--- linaro_image_tools/media_create/boards.py 2012-01-18 15:27:35 +0000
+++ linaro_image_tools/media_create/boards.py 2012-01-25 10:01:31 +0000
@@ -577,7 +577,7 @@
     @classmethod
     def add_boot_args(cls, extra_args):
         if extra_args is not None:
- cls.extra_boot_args_options += ' %s' % extra_args
+ cls.extra_boot_args_options = ' %s' % extra_args

     @classmethod
     def add_boot_args_from_file(cls, path):