11.1-PRERELEASE, waagent crashes attaching reosurce disc in Azure

[Pete French]

A bit more investigation on this and I think I found what the differece is
at least. waagent is using camcontrol periphlist 3:1:0 to find devices,
and this has chnaged from placing the discs before the pass
devices to afterwards. So on an earlier version I get this:

	root at joanna-may:/home/webadmin # camcontrol periphlist 3:1:0
	da1:  generation: 4 index: 1 status: MORE
	pass1:  generation: 4 index: 2 status: LAST

and on the box with the issue it does this:

	root at backup-db:/home/webadmin # camcontrol periphlist 3:1:0
	pass1:  generation: 4 index: 1 status: MORE
	da1:  generation: 4 index: 2 status: LAST

So that box finds 'pass1' as the device when it should be finding 'da1'
which leads to the error. I have a vague memory of seeing a commit for this
go past too.

On the other hand, the oython looks like it shuold handle this, as it
appears to try and detect which devices are disks from the output of
gpart list, which should not let it use pass1 as if it was a disc.

-pete.