az vmss update fails when trying to update image url for VM scale set

[bishal-pdMSFT]

I am trying to update os image used in my VMSS, and ran following command but it fails:
az vmss update -g myrg -n myvmss --set virtualMachineProfile.storageProfile.osDisk.image.uri=https://mystorage.blob.core.windows.net/system/Microsoft.Compute/Images/vsts-buildimagetask/Release-2-osDisk.6efa6e4e-d44c-4554-bee5-d32361220902.vhd

Error is:
create_or_update() takes at least 4 arguments (3 given)
Traceback (most recent call last):
File "/opt/az/local/lib/python2.7/site-packages/azure/cli/main.py", line 37, in main
cmd_result = APPLICATION.execute(args)
File "/opt/az/local/lib/python2.7/site-packages/azure/cli/core/application.py", line 157, in execute
result = expanded_arg.func(params)
File "/opt/az/local/lib/python2.7/site-packages/azure/cli/core/commands/arm.py", line 309, in handler
opres = setter(client, **setterargs) if client else setter(**setterargs)
File "/opt/az/local/lib/python2.7/site-packages/azure/cli/command_modules/vm/custom.py", line 1490, in vmss_set
raw=no_wait, **kwargs)
TypeError: create_or_update() takes at least 4 arguments (3 given)

log file gist: https://gist.githubusercontent.com/bishal-pdMSFT/ffd9aa642a43de16ed56a9f887734e51/raw/2c708c0e2c281401c05ca9dad277f23d68d707d6/AzCliVmssUpdateError

Environment summary

Install Method: How did you install the CLI? (e.g. pip, interactive script, apt-get, Docker, MSI, nightly)
Answer here: apt-get

CLI Version: What version of the CLI and modules are installed? (Available with az --version)
Answer here: 2.0.2

OS Version: What OS and version are you using?
Answer here: Ubuntu 14.04

Shell Type: What shell are you using? (e.g. bash, cmd.exe, PowerShell)
Answer here: bash

Description

[bishal-pdMSFT]

FYI..This is a regression. Same command was working fine in earlier version of az cli.

[tjprescott]

I've also confirmed this affects vm availability-set update.