stestr shell help doesn't work

[mtreinish]

When running the stestr shell (by just running stestr with no commands) the help command doesn't work for any of the commands. For example:

(stestr) help failing
Traceback (most recent call last):
  File "/home/computertreker/.venvs/venv2/lib/python2.7/site-packages/cmd2.py", line 786, in onecmd_plus_hooks
    stop = self.onecmd(statement)
  File "/home/computertreker/.venvs/venv2/lib/python2.7/site-packages/cmd2.py", line 974, in onecmd
    stop = func(statement)
  File "/home/computertreker/.venvs/venv2/lib/python2.7/site-packages/cliff/interactive.py", line 114, in do_help
    self.default(self.parsed('help ' + arg))
AttributeError: InteractiveApp instance has no attribute 'parsed'
EXCEPTION of type 'AttributeError' occurred with message: 'InteractiveApp instance has no attribute 'parsed''
To enable full traceback, run the following command:  'set debug true

[masayukig]

FYI.
I was thinking this is related to #145 issue. But when I changed this to cmd2 0.7.9, it still happened..

Another related thing:

cmd2: 0.8.0
$ stestr
(stestr) help 
ERROR: Invalid syntax: list.remove(x): x not in list

cmd2: 0.7.9 (works well)
(stestr) help

Shell commands (type help <topic>):
===================================
cmdenvironment  exit  history  py        quit  save  shell      show
edit            help  load     pyscript  run   set   shortcuts

Application commands (type help <topic>):
=========================================
complete  failing  help  init  last  list  load  run  slowest

[masayukig]

This seems like not stestr issue.. (cliff's issue?)

$ cliffdemo
(cliffdemo) help file
EXCEPTION of type 'AttributeError' occurred with message: 'InteractiveApp instance has no attribute 'parsed''
To enable full traceback, run the following command:  'set debug true'
(cliffdemo) set debug true
debug - was: False
now: True
(cliffdemo) help file
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/cmd2.py", line 981, in onecmd_plus_hooks
    stop = self.onecmd(statement)
  File "build/bdist.linux-x86_64/egg/cmd2.py", line 1179, in onecmd
    stop = func(statement)
  File "/home/masayuki/git/openstack/cliff/.venv/lib/python2.7/site-packages/cliff-2.11.0-py2.7.egg/cliff/interactive.py", line 114, in do_help
    self.default(self.parsed('help ' + arg))
AttributeError: InteractiveApp instance has no attribute 'parsed'
EXCEPTION of type 'AttributeError' occurred with message: 'InteractiveApp instance has no attribute 'parsed''
To enable full traceback, run the following command:  'set debug true'

[masayukig]

Now, this works on python2.7 but not on 3.7.. :(

$ python --version
Python 2.7.16
(stestr) help failing
usage: failing [-h] [--subunit] [--list]

Show the current failures known by the repository. Without --subunit, the
<snip>

$ python --version
Python 3.7.3
$ stestr
(stestr) set debug true
debug - was: False
now: True
(stestr) help failing
Traceback (most recent call last):
  File "/home/masayuki/git/stestr/.tox/py37/lib/python3.7/site-packages/cmd2/cmd2.py", line 1750, in onecmd_plus_hooks
    statement = self.precmd(statement)
  File "/home/masayuki/git/stestr/.tox/py37/lib/python3.7/site-packages/cliff/interactive.py", line 172, in precmd
    statement.command = cmd_name
  File "/home/masayuki/git/stestr/.tox/py37/lib/python3.7/site-packages/attr/_make.py", line 428, in _frozen_setattrs
    raise FrozenInstanceError()
attr.exceptions.FrozenInstanceError
EXCEPTION of type 'FrozenInstanceError' occurred with message: ''