Code review comment for ~jibel/curtin/+git/add-layer-images-support:master

@Didier,

(Note I did type incorrectly previously with 'fsimage://http://'
the shortcut fsimage http support is like fsimage:http://).

I agree I don't really understand how _get_image_paths works.
But that isn't really my issue.

The issue is that the support added for layered images
relies upon doing a directory listing of its input
(via glob.glob1 call in _get_image_paths).

That means that fsimage:http://example.com/your/path/to/some/layered.fs
will not work because we can't do a listing of the contents on
http://example.com/your/path/to/some .

Rather than extending fsimage: to work for layered filesystem images
that are local and fail in an inconsistent way for remote layeredd filesystem
images, I'd prefer either:
 a.) to add support for 'fsimage-layered:' that supports only local
     filesystems and errors if provided with a fsimage-layered:http://..
or
 b.) to add some mechanism for "list"ing a remote layered image. That
     is what I was suggesting with the index.