Netflix/aminator — pull request #107 by mrowe (2013-06-14 03:36:31+00:00)
Title: Block device mappings should not be required.

If the tagging_ebs finalizer plugin's config is overwritten to remove
the "ephemeral" mappings (thereby setting default_block_device_map to
None), _make_block_device_map would blow up. This patch checks for
None before trying to iterate.