Role assignment list includes classic administrators from the wrong scope

[dzsibi]

Describe the bug

When using az role assignment list with both --scope and --include-classic-administrators, classic administrators are shown for the current subscription, not taking the subscription specified in the scope into account.

To Reproduce:

• Create two Azure subscriptions
• az account set --subscription <first-subscription-id>
• az role assignment list --scope "/subscriptions/<second-subscription-id>" --include-classic-administrators

Output will look something like this (some properties were truncated):

[
  {
    "id": "/subscriptions/<second-subscription-id>/providers/Microsoft.Authorization/roleAssignments/<assignment-id>",
    "name": "<assignment id>",
    "scope": "/subscriptions/<second-subscription-id>",
    ...
  },
  {
    "id": "NA(classic admins)",
    "name": "NA(classic admins)",
    "scope": "/subscriptions/<first-subscription-id>",
    ...
  }
]

Expected Behavior

Roles and custom administrators from the second subscription are shown.

Environment Summary

Windows-10-10.0.19041-SP0
Python 3.6.8
Installer: MSI

azure-cli 2.15.1

[yonzhan]

RBAC