vips_class_map_all() was broken

ChangeLog

@@ -2,6 +2,7 @@
 - fallback vips_init() 
 - im_openout() compat stub was wrong, breaking ruby-vips
 - vips_class_map_concrete_all() needed a compat macro too
+- vips_class_map_all() was broken
 
 10/8/11 started 7.26.3
 - don't use G_VALUE_COLLECT_INIT(), many platforms do not have a glib this

libvips/iofuncs/object.c

@@ -1598,14 +1598,22 @@ vips_class_map_all( GType type, VipsClassMap fn, void *a )
 {
 	void *result;
 
-	/* We never unref this ref, but we never unload classes
-	 * anyway, so so what.
+	/* We can't instantiate abstract classes.
 	 */
-	if( !(result = fn( VIPS_OBJECT_CLASS( g_type_class_ref( type ) ), a )) )
-		result = vips_type_map( type, 
-			(VipsTypeMap2) vips_class_map_all, fn, a );
+	if( !G_TYPE_IS_ABSTRACT( type ) ) {
+		/* We never unref this ref, but we never unload classes
+		 * anyway, so so what.
+		 */
+		if( (result = fn( 
+			VIPS_OBJECT_CLASS( g_type_class_ref( type ) ), a )) )
+			return( result );
+	}
 
-	return( result );
+	if( (result = vips_type_map( type, 
+		(VipsTypeMap2) vips_class_map_all, fn, a )) )
+		return( result );
+
+	return( NULL );
 }
 
 /* How deeply nested is a class ... used to indent class lists.