Description of problem:

[root@ipa63server ~]# ipa cert-revoke 5 3 --revocation-reason=6
ipa: ERROR: command 'cert_revoke' takes at most 1 argument

Here error message looks not correct as cert_revoke takes 2 arguments which are as follows.
 1. SERIAL-NUMER
 2. --revocation-reason

if --revocation-reason not provided , default value "0" is picked.

[root@ipa63server ~]# ipa help cert-revoke
Purpose: Revoke a certificate.
Usage: ipa [global-options] cert-revoke SERIAL-NUMBER [options]

Positional arguments:
  SERIAL-NUMBER         Serial number in decimal or if prefixed with 0x in
                        hexadecimal

Options:
  -h, --help            show this help message and exit
  --revocation-reason=INT
                        Reason for revoking the certificate (0-10)
[root@ipa63server ~]#

Version-Release number of selected component (if applicable):
[root@ipa63server ~]# rpm -q ipa-server
ipa-server-2.2.0-5.el6.x86_64
[root@ipa63server ~]#

How reproducible:
Always

Steps to Reproduce:
1.Run following command after ipa-server-install and observe

[root@ipa63server ~]# ipa cert-revoke 5 3 --revocation-reason=6
  
Actual results:
[root@ipa63server ~]# ipa cert-revoke 5 3 --revocation-reason=6
ipa: ERROR: command 'cert_revoke' takes at most 1 argument

Expected results:
Error message should be like 
"ipa: ERROR: command 'cert_revoke' takes at most 2 argument"