Packer: MissingParameter ebs error when using ami_block_device_mappings with volume_type

Greetings!

When using ami_block_device_mappings or launch_block_device_mappings and a volume_type of gp2/io1 I get a MissingParameter ... ebs error during packer build. Omitting the volume_type allows the AMI to be built, but we want to use specific volume types.

• Packer Version: v0.10.1
• Platform: Linux amd64 and Darwin64
• Debug log output: https://gist.githubusercontent.com/PartyImp/31abba9c3da89d340ad6c582fac6da33/raw/8214964cfda5ba18ffd09fd6466f15446a4bdc8e/PACKER_LOG=1%2520packer%2520build%2520-debug%2520output
• scripts_ needed to reproduce the bug: https://gist.githubusercontent.com/PartyImp/31abba9c3da89d340ad6c582fac6da33/raw/8214964cfda5ba18ffd09fd6466f15446a4bdc8e/Example%2520Template,%2520AMI%2520is%2520the%2520official%2520ubuntu%2520ami

The error:

$ packer build example_gold.json
amazon-ebs output will be in this color.

==> amazon-ebs: Prevalidating AMI Name...
==> amazon-ebs: Inspecting the source AMI...
==> amazon-ebs: Creating temporary security group for this instance...
==> amazon-ebs: Authorizing access to port 22 the temporary security group...
==> amazon-ebs: Launching a source AWS instance...
==> amazon-ebs: Error launching source instance: MissingParameter: The request must contain the parameter ebs
==> amazon-ebs:     status code: 400, request id:
==> amazon-ebs: No AMIs to cleanup
==> amazon-ebs: Deleting temporary security group...
Build 'amazon-ebs' errored: Error launching source instance: MissingParameter: The request must contain the parameter ebs
    status code: 400, request id:

==> Some builds didn't complete successfully and had errors:
--> amazon-ebs: Error launching source instance: MissingParameter: The request must contain the parameter ebs
    status code: 400, request id:

==> Builds finished but no artifacts were created.

I think the intent with this template is to build an instance with 24gb / on gp storage, but launch then as io2:250iops later on. I don't think ami_block_device_mappings has any effect in this scenario.

There were more block devices defined, but during the course of my troubleshooting I found that I could reproduce the issue with only one block device.

Are ami_block_device_mappings and launch_block_device_mappings sections being used improperly?

Unfortunately I do have to report that packer_0.8.6 and 0.9.0 do not behave the same way; these versions successfully build the ami.

$ ~/Downloads/packer_0.8.6_darwin_amd64/packer build example_gold.json
amazon-ebs output will be in this color.

==> amazon-ebs: Prevalidating AMI Name...
==> amazon-ebs: Inspecting the source AMI...
==> amazon-ebs: Creating temporary security group for this instance...
==> amazon-ebs: Authorizing access to port 22 the temporary security group...
==> amazon-ebs: Launching a source AWS instance...
    amazon-ebs: Instance ID: i-666
==> amazon-ebs: Waiting for instance (i-666) to become ready...

Thanks very much