moutnroot failing on zpools in Azure after upgrade from 10 to 11 due to lack of waiting for da0

[Pete French]

> Are you sure the above transcript is right?  There are three reasons
> I'm asking.  First, you'll see the "Root mount waiting" message,
> which means the root mount code is, well, waiting for storvsc, exactly
> as expected.  Second - there is no "Trying to mount root".  But most
> of all - for some reason the "Mounting failed" is shown _before_ the
> "Root mount waiting", and I have no idea how this could ever happen.

OK, that's interesting, and kind of worrying! I belive, it's correct - I
have put the full trascript up here for you so you can see all of it:

https://www.twisted.org.uk/~pete/914893a3-249e-4a91-851c-f467fc185eec.txt

I am assuming that Azure's capturing of the outut is correct....

-pete.