there is useless 'u' in the wrong info when execute a wrong neutron command

[Summary]
there is useless 'u' in the wrong info when execute a wrong neutron command

[Topo]
devstack all-in-one node

[Description and expect result]
no useless 'u' in the wrong info when execute a wrong neutron command

[Reproduceable or not]
reproduceable

[Recreate Steps]
1) there is useless 'u' in the wrong info when execute a wrong neutron command:
root@45-59:/opt/stack/devstack# neutron wrongcmd
Unknown command [u'wrongcmd'] >>>ISSUE
root@45-59:/opt/stack/devstack#

2)below is a correct example for reference:
root@45-59:/opt/stack/devstack# keystone wrongcmd
usage: keystone [--version] [--debug] [--os-username <auth-user-name>]
                [--os-password <auth-password>]
                [--os-tenant-name <auth-tenant-name>]
                [--os-tenant-id <tenant-id>] [--os-auth-url <auth-url>]
                [--os-region-name <region-name>]
                [--os-identity-api-version <identity-api-version>]
                [--os-token <service-token>]
                [--os-endpoint <service-endpoint>] [--os-cache]
                [--force-new-token] [--stale-duration <seconds>] [--insecure]
                [--os-cacert <ca-certificate>] [--os-cert <certificate>]
                [--os-key <key>] [--timeout <seconds>]
                <subcommand> ...
keystone: error: argument <subcommand>: invalid choice: 'wrongcmd'

[Configration]
reproduceable bug, no need

[logs]
reproduceable bug, no need

[Root cause anlyze or debug inf]
reproduceable bug

[Attachment]
None