Code review comment for ~bitfehler/cloud-init:bitfehler/load_seed

Hi,

I previously wrote a message to the mailing list, but without any response so far, so I figured I'd write some more code and try this way. Happy about any suggestions for improvements or guidance for other approaches.

Some notes right away:
 - The "xenial" tox env does not work for me, even on clean master, is this a known issue?
 - I thought it would be nice to make a holistic change (i.e. changing all callers to the new function), but in fact I do not have access to a test setup for the OVH or CloudStack data sources. How is this usually handled? Is it preferable to not touch any data sources you can not test? Or are there means for this to be tested before it lands in a release?

Thanks a bunch,
Conrad