`az acr repository delete` fails with exception

Description

Outline the issue here:

I am executing ac acr repository delete and the command is failing with the following exception:

$ az acr repository delete -n myRegistry -u myUser -p myPass --repository myorg/myrepo

'NoneType' object has no attribute 'tier'
Traceback (most recent call last):
  File "/usr/lib64/az/lib/python2.7/site-packages/azure/cli/main.py", line 36, in main
    cmd_result = APPLICATION.execute(args)
  File "/usr/lib64/az/lib/python2.7/site-packages/azure/cli/core/application.py", line 212, in execute
    result = expanded_arg.func(params)
  File "/usr/lib64/az/lib/python2.7/site-packages/azure/cli/core/commands/__init__.py", line 377, in __call__
    return self.handler(*args, **kwargs)
  File "/usr/lib64/az/lib/python2.7/site-packages/azure/cli/core/commands/__init__.py", line 626, in _execute_command
    reraise(*sys.exc_info())
  File "/usr/lib64/az/lib/python2.7/site-packages/azure/cli/core/commands/__init__.py", line 603, in _execute_command
    result = op(client, **kwargs) if client else op(**kwargs)
  File "/usr/lib64/az/lib/python2.7/site-packages/azure/cli/command_modules/acr/repository.py", line 281, in acr_repository_delete
    registry_name, resource_group_name, DELETE_NOT_SUPPORTED)
  File "/usr/lib64/az/lib/python2.7/site-packages/azure/cli/command_modules/acr/_utils.py", line 286, in managed_registry_validation
    if arm_resource.sku.tier == SkuTier.basic.value:
AttributeError: 'NoneType' object has no attribute 'tier'

NOTE that the SKU of the registry is “Classic” – it was created a while ago.

---

Environment summary

Install Method: How did you install the CLI? (e.g. pip, interactive script, apt-get, Docker, MSI, nightly)
Answer here: rpm on Fedora 26

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

az --version
azure-cli (2.0.17)

acr (2.0.11)
acs (2.0.15)
appservice (0.1.16)
batch (3.1.3)
billing (0.1.4)
cdn (0.0.8)
cloud (2.0.7)
cognitiveservices (0.1.7)
command-modules-nspkg (2.0.1)
component (2.0.7)
configure (2.0.10)
consumption (0.1.4)
container (0.1.10)
core (2.0.16)
cosmosdb (0.1.12)
dla (0.0.11)
dls (0.0.13)
eventgrid (0.1.3)
extension (0.0.2)
feedback (2.0.6)
find (0.2.6)
interactive (0.3.9)
iot (0.1.11)
keyvault (2.0.10)
lab (0.0.10)
monitor (0.0.9)
network (2.0.14)
nspkg (3.0.1)
profile (2.0.12)
rdbms (0.0.6)
redis (0.2.8)
resource (2.0.14)
role (2.0.11)
servicefabric (0.0.3)
sf (1.0.8)
sql (2.0.11)
storage (2.0.15)
vm (2.0.14)

Python location '/usr/lib64/az/bin/python'
Extensions directory '/home/raman/.azure/cliextensions'

Python (Linux) 2.7.13 (default, Sep  5 2017, 08:53:59) 
[GCC 7.1.1 20170622 (Red Hat 7.1.1-3)]

Legal docs and information: aka.ms/AzureCliLegal

OS Version: What OS and version are you using?
Answer here: Fedora 26

Shell Type: What shell are you using? (e.g. bash, cmd.exe, Bash on Windows)
Answer here: fish (bash also doesn’t work)

[djyou]

@rocketraman Since you mentioned Classic, did you create the registry from Azure Portal? In this case ARM didn’t return the SKU properly. Do you mind sharing your registry name or login URI so we can investigate? My email is [e-mail] if you would like to send it privately. Thank you.

Also Classic/Basic registries don’t support deleting repositories or images, which is the exact intent of this check.

/cc @SajayAntony

[troydai]

@djyou since this is a solvable issue, I will assign this to the next milestone. Thanks.