Code review comment for ~thedac/simplestreams:bug/1790904

> @thedac,
> please comment on the size/hash. Doesnt that seem just wrong to you?
> The only way to test if something went wrong in the upload is to launch it?

@smoser

I have scoured the glance v2 api documentation [0]. The API has changed such
that we cannot send the expected checksum during the creation/upload process.

For instance the glanceclient.images.data method is for downloading an image.
None of the create, upload or update methods take a checksum.

What we can do is validate the checksum *after* we upload it. Let me know if
something like [1] will work for you or please suggest/implement a validation.

[0] https://docs.openstack.org/python-glanceclient/latest/reference/api/glanceclient.v2.images.html
[1] https://pastebin.ubuntu.com/p/jH8fNWj5jJ/