Remove ugly argumentparser bug

Before:

[21:09] bento:~% cdist
Traceback (most recent call last):
  File "/home/users/nico/p/cdist/cdist/bin/../scripts/cdist", line 232, in <module>
    commandline()
  File "/home/users/nico/p/cdist/cdist/bin/../scripts/cdist", line 106, in commandline
    args.func(args)
AttributeError: 'Namespace' object has no attribute 'func'

After:

[21:11] bento:~% cdist
usage: cdist [-h] [-d] [-v] [-V] {banner,config} ...

cdist 2.1.1-48-gfd72c60

optional arguments:
  -h, --help       show this help message and exit
  -d, --debug      Set log level to debug
  -v, --verbose    Set log level to info, be more verbose
  -V, --version    Show version

Commands:
  {banner,config}

Get cdist at http://www.nico.schottelius.org/software/cdist/
[21:11] bento:~%

Signed-off-by: Nico Schottelius <nico@bento.schottelius.org>

scripts/cdist

@@ -103,7 +103,14 @@ def commandline():
         logging.root.setLevel(logging.DEBUG)
 
     log.debug(args)
-    args.func(args)
+
+    # Work around python 3.3 bug:
+    # http://bugs.python.org/issue16308
+    # http://bugs.python.org/issue9253
+    try:
+        args.func(args)
+    except AttributeError:
+        parser['main'].print_help()
 
 def config(args):
     configinstall(args, mode=cdist.config.Config)