Fixed a bug in constant folding of keyword arguments to filter calls.  Thanks noskolo.

--HG--
branch : trunk
diff --git a/tests/test_old_bugs.py b/tests/test_old_bugs.py
new file mode 100644
index 0000000..08db225
--- /dev/null
+++ b/tests/test_old_bugs.py
@@ -0,0 +1,18 @@
+# -*- coding: utf-8 -*-
+"""
+    Tests for old bugs
+    ~~~~~~~~~~~~~~~~~~
+
+    Unittest that test situations caused by various older bugs.
+
+    :copyright: Copyright 2008 by Armin Ronacher.
+    :license: BSD.
+"""
+from jinja2 import Environment
+
+def test_keyword_folding():
+    env = Environment()
+    env.filters['testing'] = lambda value, some: value + some
+    assert env.from_string("{{ 'test'|testing(some='stuff') }}") \
+           .render() == 'teststuff'
+