Skip templates with syntax errors on babel extract

--HG--
branch : trunk
diff --git a/jinja2/ext.py b/jinja2/ext.py
index 4d68983..0f30d54 100644
--- a/jinja2/ext.py
+++ b/jinja2/ext.py
@@ -425,7 +425,11 @@
     )
 
     source = fileobj.read().decode(options.get('encoding', 'utf-8'))
-    node = environment.parse(source)
+    try:
+        node = environment.parse(source)
+    except TemplateSyntaxError, e:
+        # skip templates with syntax errors
+        return
     for lineno, func, message in extract_from_ast(node, keywords):
         yield lineno, func, message, []