fixed. "nothing" is defined as:

    null_actor const nothing = null_actor();
which doesn't make it an actor, rather an "actor base".

Shouldn't it rather be defined as something like:
    actor<null_actor> const nothing = null_actor();

[SVN r51421]

libs/spirit

@@ -1 +1 @@
-Subproject commit c0b6fdef5f8d8be8da11c23a3473960c2cf78012
+Subproject commit ce293871ba9139e00cb7549a57b51d04eb86b8fd