Bug fix -- we weren't handling NULL keywords dictionaries in raw_function

[SVN r19359]

include/boost/python/raw_function.hpp

@@ -29,7 +29,10 @@ namespace detail
       {
           return incref(
               object(
-                  f(tuple(borrowed_reference(args)), dict(borrowed_reference(keywords)))
+                  f(
+                      tuple(borrowed_reference(args))
+                    , keywords ? dict(borrowed_reference(keywords)) : dict()
+                  )
               ).ptr()
           );
       }

test/args.cpp

@@ -90,3 +90,5 @@ BOOST_PYTHON_MODULE(args_ext)
 
     def("inner", &X::inner, "docstring", args("self", "n"), return_internal_reference<>());
 }
+
+#include "module_tail.cpp"

test/args.py

@@ -4,6 +4,14 @@
 >>> raw(3, 4, foo = 'bar', baz = 42)
 ((3, 4), {'foo': 'bar', 'baz': 42})
 
+   Prove that we can handle empty keywords and non-keywords
+   
+>>> raw(3, 4)
+((3, 4), {})
+
+>>> raw(foo = 'bar')
+((), {'foo': 'bar'})
+
 >>> f(x= 1, y = 3, z = 'hello')
 (1, 3.0, 'hello')