desired azure cleanups

[Scott Moser]

When doing some recent cleanups of azure datasource, we found a couple desires
a.) it'd be nice if cloud-init automatically used 'fabric' if no agent (waagent) was available.
b.) I didn't understand why we have a test test_exception_fetching_fabric_data_doesnt_propagate
    if we failed to fetch data, why do we just log exception rather than raising error.

[Dan Watkins (oddbloke)]

On 22/08/16 21:36, Launchpad Bug Tracker wrote:
> b.) I didn't understand why we have a test test_exception_fetching_fabric_data_doesnt_propagate
> if we failed to fetch data, why do we just log exception rather than raising error.

09:15:33 Odd_Bloke | smoser: I haven't looked at it, but my
recollection of test_exception_fetching_fabric_data_doesnt_propagate is
that data sources shouldn't raise exceptions.
09:22:17 Odd_Bloke | Reading cloudinit.sources.find_source, that isn't
true.
09:22:22 Odd_Bloke | But I believe that was the motivation behind it.

Also worth noting that we log the exception and immediately return
False, so the effect is identical to not catching it.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/2709