Do not iterate action.choices if it is none

Do not iterate action.choices in the method add_arguments
in the class OpenStackHelpFormatter if action.choices is
not iterable because it is none.

Change-Id: Ie7110adb798326e5856fddfb6a7365c663b84998
Closes-Bug: #1372152

keystoneclient/shell.py

@@ -443,6 +443,8 @@ class OpenStackHelpFormatter(argparse.HelpFormatter):
 
     def add_arguments(self, actions):
         for action in filter(lambda x: not x.option_strings, actions):
+            if not action.choices:
+                continue
             for choice in action.choices:
                 length = len(choice) + self.INDENT_BEFORE_ARGUMENTS
                 if(length > self._max_help_position and

keystoneclient/tests/test_shell.py

@@ -115,6 +115,12 @@ class ShellTest(utils.TestCase):
         self.assertThat(help_text,
                         matchers.MatchesRegex(required))
 
+    def test_help_command_with_no_action_choices(self):
+        required = 'usage: keystone user-update'
+        help_text = self.shell('help user-update')
+        self.assertThat(help_text,
+                        matchers.MatchesRegex(required))
+
     def test_auth_no_credentials(self):
         with testtools.ExpectedException(
                 exceptions.CommandError, 'Expecting'):