Make positional args check more robust. (Azure#6244)

Whatever is wrong with the CI that it keeps timing out the build, it doesn't have anything to do with this PR.  If it does this PR could be reverted.

src/azure-cli-core/azure/cli/core/commands/parameters.py

@@ -386,7 +386,7 @@ def positional(self, dest, arg_type=None, **kwargs):
         # registered for this command.
         command_args = self.command_loader.argument_registry.arguments[self.scope]
         positional_args = {k: v for k, v in command_args.items() if v.settings.get('options_list') == []}
-        if positional_args:
+        if positional_args and dest not in positional_args:
             raise CLIError("command authoring error: commands may have, at most, one positional argument. '{}' already "
                            "has positional argument: {}.".format(self.scope, ' '.join(positional_args.keys())))