[IOT] Fix for iot hub policy delete, deleting all policies. (#4266)

* [IOT] Fix for iot hub policy delete, deleting all policies.

Iot hub policy delete was still deleting all policies rather
than the specified policy.

Observing the policies once seems to release the resources,
setting the desired policy list to empty [].

The fix was to pass a deepcopy of the original policy list into
_is_policy_existed to not prematurely observe the original policies.

* Added new rest recording file.

* Update to history and setup.py based on feedback.

* Changes based on feedback.

src/command_modules/azure-cli-iot/HISTORY.rst

@@ -2,6 +2,9 @@
 
 Release History
 ===============
+unreleased
++++++++++++++++
+* revisit of bug 3934 -- policy creation no longer clears existing policies.
 
 0.1.10 (2017-07-27)
 +++++++++++++++++++

src/command_modules/azure-cli-iot/azure/cli/command_modules/iot/custom.py

@@ -148,9 +148,10 @@ def iot_hub_policy_create(client, hub_name, policy_name, permissions, resource_g
 
 
 def iot_hub_policy_delete(client, hub_name, policy_name, resource_group_name=None):
+    import copy
     hub = iot_hub_get(client, hub_name, resource_group_name)
     policies = iot_hub_policy_list(client, hub_name, hub.resourcegroup)
-    if not _is_policy_existed(policies, policy_name):
+    if not _is_policy_existed(copy.deepcopy(policies), policy_name):
         raise CLIError('Policy {0} not found.'.format(policy_name))
     updated_policies = [p for p in policies if p.key_name.lower() != policy_name.lower()]
     hub.properties.authorization_policies = updated_policies