[master] f233678 Add an assert for the benefit of static analysers

[Poul-Henning Kamp]

commit f2336782f6f8a51ff21d61e02e9827b212fc0108
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Sat Jun 29 11:10:09 2013 +0000

    Add an assert for the benefit of static analysers

diff --git a/include/vtree.h b/include/vtree.h
index 7692d12..84af261 100644
--- a/include/vtree.h
+++ b/include/vtree.h
@@ -584,8 +584,10 @@ name##_VRB_REMOVE(struct name *head, struct type *elm)			\
 	} else								\
 		VRB_ROOT(head) = child;					\
 color:									\
-	if (color == VRB_BLACK)						\
+	if (color == VRB_BLACK) {					\
+		AN(parent);						\
 		name##_VRB_REMOVE_COLOR(head, parent, child);		\
+	}								\
 	return (old);							\
 }									\
 									\