Description of problem:
ipa-client-install does not finish if joining to RHEL-6.8 version of
ipa-server.
Join to ipa-server from RHEL-7 is working as expected.


Protocol: TLS1.2
Cipher: TLS_RSA_WITH_AES_256_CBC_SHA
Destroyed connection context.rpcclient_37084432
Traceback (most recent call last):
  File "/usr/sbin/ipa-client-install", line 3127, in <module>
    sys.exit(main())
  File "/usr/sbin/ipa-client-install", line 3108, in main
    rval = install(options, env, fstore, statestore)
  File "/usr/sbin/ipa-client-install", line 2817, in install
    api.finalize()
  File "/usr/lib/python2.7/site-packages/ipalib/plugable.py", line 701, in
finalize
    self.__do_if_not_done('load_plugins')
  File "/usr/lib/python2.7/site-packages/ipalib/plugable.py", line 416, in
__do_if_not_done
    getattr(self, name)()
  File "/usr/lib/python2.7/site-packages/ipalib/plugable.py", line 579, in
load_plugins
    for package in self.packages:
  File "/usr/lib/python2.7/site-packages/ipalib/__init__.py", line 919, in
packages
    ipaclient.remote_plugins.get_package(self),
  File "/usr/lib/python2.7/site-packages/ipaclient/remote_plugins/__init__.py",
line 19, in get_package
    plugins = compat.get_package(api, client)
  File "/usr/lib/python2.7/site-packages/ipaclient/remote_plugins/compat.py",
line 42, in get_package
    ping = client.forward(u'ping', u'api_version', version=u'2.0')
  File "/usr/lib/python2.7/site-packages/ipalib/rpc.py", line 986, in forward
    return self._call_command(command, params)
  File "/usr/lib/python2.7/site-packages/ipalib/rpc.py", line 967, in
_call_command
    return command(*params)
  File "/usr/lib/python2.7/site-packages/ipalib/rpc.py", line 1117, in _call
    return self.__request(name, args)
  File "/usr/lib/python2.7/site-packages/ipalib/rpc.py", line 1111, in
__request
    raise error_class(**kw)
ipalib.errors.ZeroArgumentError: command 'ping' takes no arguments


Version-Release number of selected component (if applicable):
ipa-client-4.4.0-3.el7
ipa-server-3.0.0-50.el6.1

How reproducible:
always

Steps to Reproduce:
1. Just try to join