Description:
sk1 fails to start with the following traceback:

Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/usr/lib/python2.7/site-packages/sk1/__init__.py", line 21, in sk1_run
app.main.main()
File "/usr/lib/python2.7/site-packages/sk1/app/main.py", line 150, in main
application = SketchApplication(filename, options.display, options.geometry, run_script = options.run_script)
File "/usr/lib/python2.7/site-packages/sk1/app/skapp.py", line 155, in __init__
TkApplication.__init__(self, screen_name = screen_name, geometry = geometry)
File "/usr/lib/python2.7/site-packages/sk1/app/skapp.py", line 60, in __init__
self.init_tk(screen_name, geometry)
File "/usr/lib/python2.7/site-packages/sk1/app/skapp.py", line 185, in init_tk
TkApplication.init_tk(self, screen_name = screen_name, geometry = geometry)
File "/usr/lib/python2.7/site-packages/sk1/app/skapp.py", line 63, in init_tk
self.root = Tk(screenName = screen_name, baseName = self.tk_basename, className = self.tk_class_name)
File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1748, in __init__
if not sys.flags.ignore_environment:
UnboundLocalError: local variable 'sys' referenced before assignment

Additional info:
* sk1-0.9.1-11
* python2 2.7.5-2
* Up-to-date Arch x86-64

Steps to reproduce:
1) Install latest sk1 from community stable.
2) Run it.