Plumiferos bugreport:

The Blur node didn't pass on a buffer when the 'factor' value was not
exactly zero. Tiny values (like 0.0000001) or even negative ones were
still handled by the blur code.

source/blender/blenkernel/intern/armature.c

@@ -877,6 +877,7 @@ void where_is_armature_bone(Bone *bone, Bone *prevbone)
 	
 	/* Bone Space */
 	VecSubf (vec, bone->tail, bone->head);
+	printvecf(bone->name, vec);
 	vec_roll_to_mat3(vec, bone->roll, bone->bone_mat);
 
 	bone->length= VecLenf(bone->head, bone->tail);

source/blender/blenkernel/intern/node_composite.c

@@ -2839,7 +2839,7 @@ static void node_composit_exec_blur(void *data, bNode *node, bNodeStack **in, bN
 	}
 	else {
 		
-		if(in[1]->vec[0]==0.0f) {
+		if(in[1]->vec[0]<=0.001f) {	/* time node inputs can be a tiny value */
 			/* pass on image */
 			new= pass_on_compbuf(img);
 		}