Workaround for AzurePowerShell regression when populating account properties (#469)

* Add workaround for AzurePowerShell profile module regression (failure to populate account properties)

* Fix refresh token transformation

* Update error message with instructions to clear cross-process auth cache

Author: Bryant Richardson

Identity/AzureStack.Identity.psm1

@@ -437,6 +437,17 @@ function Register-AzsWithMyDirectoryTenant {
             Select -Last 1 -ExpandProperty RefreshToken |
             ConvertTo-SecureString -AsPlainText -Force
 
+        # Workaround due to regression in AzurePowerShell profile module which fails to populate the response object of "Add-AzureRmAccount" cmdlet
+        if (-not $refreshToken) {
+            if ($tokens.Count -eq 1) {
+                Write-Warning "Failed to find target refresh token from Azure PowerShell Cache; attempting to reuse the single cached auth context..."
+                $refreshToken = $tokens[0].RefreshToken | ConvertTo-SecureString -AsPlainText -Force
+            }
+            else {
+                throw "Unable to find refresh token from Azure PowerShell Cache. Please try the command again in a fresh PowerShell instance after running 'Clear-AzureRmContext -Scope CurrentUser -Force -Verbose'."
+            }
+        }
+
         return $refreshToken
     }
 
@@ -802,7 +813,18 @@ function Unregister-AzsWithMyDirectoryTenant {
             Sort ExpiresOn |
             Select -Last 1 -ExpandProperty RefreshToken |
             ConvertTo-SecureString -AsPlainText -Force
-    
+
+        # Workaround due to regression in AzurePowerShell profile module which fails to populate the response object of "Add-AzureRmAccount" cmdlet
+        if (-not $refreshToken) {
+            if ($tokens.Count -eq 1) {
+                Write-Warning "Failed to find target refresh token from Azure PowerShell Cache; attempting to reuse the single cached auth context..."
+                $refreshToken = $tokens[0].RefreshToken | ConvertTo-SecureString -AsPlainText -Force
+            }
+            else {
+                throw "Unable to find refresh token from Azure PowerShell Cache. Please try the command again in a fresh PowerShell instance after running 'Clear-AzureRmContext -Scope CurrentUser -Force -Verbose'."
+            }
+        }
+
         return $refreshToken
     }