stats plugin must be a prerequiste

When trying a manual build or bzr-gtk, bzrlib.plugins.stats break the build.

How to reproduce :
> cd ~/.bazaar/plugins
> bzr branch lp:bzr-gtk gtk
> cd btk
> python setup.py build

(my objective was maily to build the locale files)

Traceback :
Traceback (most recent call last):
  File "setup.py", line 169, in <module>
    'check': Check}
  File "/usr/lib64/python2.6/distutils/core.py", line 152, in setup
    dist.run_commands()
  File "/usr/lib64/python2.6/distutils/dist.py", line 975, in run_commands
    self.run_command(cmd)
  File "/usr/lib64/python2.6/distutils/dist.py", line 995, in run_command
    cmd_obj.run()
  File "/usr/lib64/python2.6/distutils/command/build.py", line 134, in run
    self.run_command(cmd_name)
  File "/usr/lib64/python2.6/distutils/cmd.py", line 333, in run_command
    self.distribution.run_command(command)
  File "/usr/lib64/python2.6/distutils/dist.py", line 995, in run_command
    cmd_obj.run()
  File "setup.py", line 54, in run
    from bzrlib.plugins.stats.cmds import find_credits
ImportError: No module named stats.cmds

Software versions :
Python 2.6.2
Bazaar 2.1.0
bzr-gtk r700

How to solve :
- add a try except or the prerequiste in the setup.py file

Workaround
- install first and build bzr-stats plugin