Description of problem:
user-mod --rename is successful for more than 32 characters.

Version-Release number of selected component (if applicable):
ipa-server-2.2.0-4.el6.x86_64

How reproducible:


Steps to Reproduce:
1.# ipa user-mod --rename=max32charactersmax32charactersmax sup34
---------------------
Modified user "sup34"
---------------------
  User login: max32charactersmax32charactersmax
  First name: Superuser
  Last name: crazylastnametoolong
  Home directory: /home2/sup34
  Login shell: /bin/sh
  Email address: sup34@really.cool.domain.co.uk.us.fi.com
  UID: 243400008
  GID: 243400008
  Telephone Number: 9999999999
  Account disabled: False
  Password: False
  Member of groups: ipausers
  Kerberos keys available: False

# ipa user-mod --rename=max32charactersmax32charactersmax123456789
max32charactersmax32charactersmax
-------------------------------------------------
Modified user "max32charactersmax32charactersmax"
-------------------------------------------------
  User login: max32charactersmax32charactersmax123456789
  First name: Superuser
  Last name: crazylastnametoolong
  Home directory: /home2/sup34
  Login shell: /bin/sh
  Email address: sup34@really.cool.domain.co.uk.us.fi.com
  UID: 243400008
  GID: 243400008
  Telephone Number: 9999999999
  Account disabled: False
  Password: False
  Member of groups: ipausers
  Kerberos keys available: False

Observed that user-add does not allow more than 32 characters:
# ipa user-add max32charactersmax32charactersmax
First name: superuser
Last name: crazylastname2
ipa: ERROR: invalid 'login': can be at most 32 characters


Actual results:
user-mod --rename allows login name with more than 32 characters.

Expected results:
user-mod --rename login name should be at most 32 characters. Should throw
error if there is more than 32 characters.

Additional info: