"sfdisk" on Ubuntu 16.04 breaks filesystem detection

[imTigger]

How to reproduce:
Deploy an Ubuntu 16.04 machine on Azure, set

ResourceDisk.Format=y

It doesn't format the resource disk as documented

Problem:
"sfdisk -c" emits deprecated warning

sfdisk: --id is deprecated in favour of --part-type

Furthermore, "sfdisk --part-type" output with leading space " 7" therefore rstrip won't work.

https://github.com/Azure/WALinuxAgent/blob/47442f76a98e2fd647bf8d3099d5354529dfa03b/azurelinuxagent/daemon/resourcedisk/default.py

Impact:
Resource disk with ntfs filesystem is not detected and mkfs-ed, and mounted as-is

[alyukhan]

We observing this issue with increasing frequency on Ubuntu 16.04 as sell.

[jinhyunr]

What version of waagent are you seeing this issue? If the version is not 2.2, does updating to the latest ver, 2.2, fix the issue?

[imTigger]

Yes, problem does persist in 2.2.0

2016/11/01 14:34:37.466152 INFO Activate resource disk
2016/11/01 14:34:37.487227 INFO Detect GPT...
2016/11/01 14:34:37.653683 INFO GPT not detected
2016/11/01 14:34:37.666371 INFO Check fstype
2016/11/01 14:34:37.685410 INFO Mount resource disk
2016/11/01 14:34:37.731627 INFO Resource disk (/dev/sdb) is mounted at /mnt with fstype ext4
2016/11/01 14:34:37.754025 WARNING Failed to write data loss warnning:[Errno 30] Read-only file system: '/mnt/DATALOSS_WARNING_README.txt'
2016/11/01 14:34:37.781241 INFO Enable swap
2016/11/01 14:34:37.798038 INFO Create swap file
2016/11/01 14:34:37.810941 ERROR run cmd 'dd if=/dev/zero of=/mnt/swapfile bs=1024 count=20971520' failed
2016/11/01 14:34:37.843744 ERROR Error Code:1
2016/11/01 14:34:37.858728 ERROR Result:dd: failed to open '/mnt/swapfile': Read-only file system

2016/11/01 14:34:37.897843 ERROR run cmd 'mkswap /mnt/swapfile' failed
2016/11/01 14:34:37.918128 ERROR Error Code:1
2016/11/01 14:34:37.930051 ERROR Result:mkswap: cannot open /mnt/swapfile: No such file or directory

2016/11/01 14:34:37.958108 ERROR run cmd 'swapon /mnt/swapfile' failed
2016/11/01 14:34:37.974239 ERROR Error Code:255
2016/11/01 14:34:37.981251 ERROR Result:swapon: stat of /mnt/swapfile failed: No such file or directory

2016/11/01 14:34:37.993521 ERROR Failed to enable swap (000005)/mnt/swapfile

...

root@hostname:~/WALinuxAgent-2.2.0# lsblk -f
NAME   FSTYPE LABEL             UUID                                 MOUNTPOINT
fd0
sda
└─sda1 ext4   cloudimg-rootfs   a01e2ccd-9f22-4bd5-9515-6a83c8e13966 /
sdb
└─sdb1 ntfs   Temporary Storage DEE28C59E28C37B3                     /mnt

root@hostname:~/WALinuxAgent-2.2.0# waagent -version
WALinuxAgent-2.2.0 running on ubuntu 16.04
Python: 2.7.12
Goal state agent: 2.2.0