Description of problem:
When calling IPA command 'ipa help' for the first time the traceback is shown
instead of valid output.

Version-Release number of selected component (if applicable):
ipa-4.5.0-21.el7_4.1 and all older ipa-4.5.0 versions

How reproducible:
Always

Steps to Reproduce:
1. Install ipa-server
2. kinit
3. call ipa help

Actual results:
Traceback which might be seen in Additional info.

Expected results:
See help.

Additional info:

ipa: WARNING: Failed to read schema: [Errno 2] No such file or directory:
u'/home/user/.cache/ipa/schema/1/7a5de3fd'
ipa: ERROR: TypeError: 'NoneType' object has no attribute '__getitem__'
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/ipalib/cli.py", line 1351, in run
    sys.exit(api.Backend.cli.run(argv))
  File "/usr/lib/python2.7/site-packages/ipalib/cli.py", line 1101, in run
    cmd = self.get_command(argv)
  File "/usr/lib/python2.7/site-packages/ipalib/cli.py", line 1070, in
get_command
    self.Command.help(outfile=sys.stderr)
  File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 444, in
__call__
    self.ensure_finalized()
  File "/usr/lib/python2.7/site-packages/ipalib/plugable.py", line 230, in
ensure_finalized
    self.finalize()
  File "/usr/lib/python2.7/site-packages/ipalib/plugable.py", line 210, in
finalize
    self._on_finalize()
  File "/usr/lib/python2.7/site-packages/ipalib/cli.py", line 733, in
_on_finalize
    if c.NO_CLI:
  File "/usr/lib/python2.7/site-packages/ipaclient/remote_plugins/schema.py",
line 247, in NO_CLI
    halp = self._schema[self.schema_key].get_help(self.full_name)
  File "/usr/lib/python2.7/site-packages/ipaclient/remote_plugins/schema.py",
line 329, in get_help
    return self._schema.get_help(self.name, key)
  File "/usr/lib/python2.7/site-packages/ipaclient/remote_plugins/schema.py",
line 520, in get_help
    return self._help[namespace][member]
TypeError: 'NoneType' object has no attribute '__getitem__'
ipa: ERROR: an internal error has occurred