cinder.expection tries to register opt fatal_exception_format_errors twice

[wangchy]

I hit one problem caused by following source codes:

/usr/lib/python2.7/site-packages/cinder/exception.py, line 29:
========================================================
     27 from oslo_config import cfg
     28 from oslo_log import log as logging
     29 from oslo_versionedobjects import exception as obj_exc

/usr/lib/python2.7/site-packages/oslo_versionedobjects/exception.py, line 37-47:
===================================================================
     37
     38 exc_log_opts = [
     39 cfg.BoolOpt('fatal_exception_format_errors',
     40 default=False,
     41 help='Make exception message format errors fatal'),
     42 ]
     43
     44 CONF = cfg.CONF
     45 CONF.register_opts(exc_log_opts)
     46
     47

/usr/lib/python2.7/site-packages/cinder/exception.py, line 37-47
================================================================================
     37
     38 exc_log_opts = [
     39 cfg.BoolOpt('fatal_exception_format_errors',
     40 default=False,
     41 help='Make exception message format errors fatal.'),
     42 ]
     43
     44 CONF = cfg.CONF
     45 CONF.register_opts(exc_log_opts)
     46
     47

The problem is that, when I try to start service cinder-api, it fails with following error messages:
================================================
Traceback (most recent call last):
  File "/usr/bin/cinder-api", line 6, in <module>
    from cinder.cmd.api import main
  File "/usr/lib/python2.7/site-packages/cinder/cmd/api.py", line 37, in <module>
    from cinder import rpc
  File "/usr/lib/python2.7/site-packages/cinder/rpc.py", line 34, in <module>
    import cinder.context
  File "/usr/lib/python2.7/site-packages/cinder/context.py", line 27, in <module>
    from cinder import policy
  File "/usr/lib/python2.7/site-packages/cinder/policy.py", line 21, in <module>
    from cinder import exception
  File "/usr/lib/python2.7/site-packages/cinder/exception.py", line 45, in <module>
    CONF.register_opts(exc_log_opts)
  File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1791, in __inner
    result = f(self, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1948, in register_opts
    self.register_opt(opt, group, clear_cache=False)
  File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1795, in __inner
    return f(self, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1937, in register_opt
    if _is_opt_registered(self._opts, opt):
  File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 573, in _is_opt_registered
    raise DuplicateOptError(opt.name)
oslo_config.cfg.DuplicateOptError: duplicate option: fatal_exception_format_errors

Given we have switched to versionedobject, I think we need to remove the lines from cinder.exception.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/185314

[OpenStack Infra (hudson-openstack)]

Change abandoned by wangchy (<email address hidden>) on branch: master
Review: https://review.openstack.org/185314