Update project/domain member doesn't work on users whose id contains underscore, '_'.

Issue

• Update project/domain member doesn't work on users whose id contains underscore, '_'.

For example, 'test_user' is in the situation.

# keystone user-list
+----------------------------------+-------------+---------+----------------------+
|                id                |     name    | enabled |        email         |
+----------------------------------+-------------+---------+----------------------+
| f72f202202d84daba98c87b4f2c5a433 |    admin    |   True  |    root@localhost    |
| 3763354ba0f94349bc02874839cb504e |  ceilometer |   True  | ceilometer@localhost |
| eb504a706bac4e5ab44f72e85475d63c |    cinder   |   True  |   cinder@localhost   |
| 2973f013c81b4a1a958d904520aa6d37 |     demo    |   True  |                      |
| ce8bee1d215f40518974394f32d05176 |    glance   |   True  |   glance@localhost   |
| e6dbf07aade24cbeab2e6dfc4e53841c |   neutron   |   True  |  neutron@localhost   |
| 0103a7f316e8438fa8c4c460c4e3d7a8 |     nova    |   True  |    nova@localhost    |
| 3df8193e2aa44df3bd5b4764ab4c1372 |    swift    |   True  |   swift@localhost    |
| dbfd70a2dfde4cd7b2cafc7bde97b6a3 |  test_knoha |   True  |                      |
| 7974a8b7833a44608bd71258d632f691 | test_knoha1 |   True  |                      |
|            test_user             |  test_user  |   True  |                      | <--- HERE
+----------------------------------+-------------+---------+----------------------+

This issue occurs in the environment which uses identity integration with LDAP backend or Active Directory as LDAP backend when LDAP uses user id which contains underscore.