Allow blank to email in user-update

User cannot set blank to email address when use "user-update".

This patch fixes this problem.

Change-Id: I3b9494a1c668358a529031c366c55b303f43c533
Closes-bug: #1226439

keystoneclient/v2_0/shell.py

@@ -102,7 +102,7 @@ def do_user_update(kc, args):
     kwargs = {}
     if args.name:
         kwargs['name'] = args.name
-    if args.email:
+    if args.email is not None:
         kwargs['email'] = args.email
     if args.enabled:
         kwargs['enabled'] = utils.string_to_bool(args.enabled)

tests/v2_0/test_shell.py

@@ -71,7 +71,10 @@ class ShellTests(utils.TestCase):
         orig = sys.stdout
         try:
             sys.stdout = cStringIO.StringIO()
-            self.shell.main(cmd.split())
+            if isinstance(cmd, list):
+                self.shell.main(cmd)
+            else:
+                self.shell.main(cmd.split())
         except SystemExit:
             exc_type, exc_value, exc_traceback = sys.exc_info()
             self.assertEqual(exc_value.code, 0)
@@ -130,6 +133,14 @@ class ShellTests(utils.TestCase):
         out = self.run_command('user-update 1')
         self.assertThat(out, matchers.MatchesRegex(required))
 
+        self.run_command(['user-update', '--email', '', '1'])
+        self.fake_client.assert_called_anytime(
+            'PUT', '/users/1',
+            {'user':
+                {'id': '1',
+                 'email': ''}
+             })
+
     def test_role_create(self):
         self.run_command('role-create --name new-role')
         self.fake_client.assert_called_anytime(