Steps to reproduce
------------------

1. Configure client-specific logging as described in [0] by adding an include
   directive, that may or may not point to a valid filename, to smb.conf:

   include = /etc/samba/smb.conf.client-%I

2. Run: samba-tool user list


Expected results
----------------

samba-tool should ignore the failed include and show the list of
users.


Actual results
--------------

$ samba-tool user list
ERROR(runtime): uncaught exception - Unable to load default file
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/__init__.py", line 175, in _run
    return self.run(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/user.py", line 261, in run
    lp = sambaopts.get_loadparm()
  File "/usr/lib/python2.7/dist-packages/samba/getopt.py", line 92, in get_loadparm
    self._lp.load_default()


Version
-------

$ samba-tool --version
4.1.6-Debian

$ apt-cache show samba
Package: samba
Version: 2:4.1.6+dfsg-1~bpo70+1


[0] https://wiki.samba.org/index.php/Client_specific_Log