fix string manipulation in render_templatefile()

scrapy/utils/template.py

@@ -10,7 +10,8 @@ def render_templatefile(path, **kwargs):
 
     content = string.Template(raw).substitute(**kwargs)
 
-    with open(path.rstrip('.tmpl'), 'wb') as file:
+    render_path = path[:-len('.tmpl')] if path.endswith('.tmpl') else path
+    with open(render_path, 'wb') as file:
         file.write(content)
     if path.endswith('.tmpl'):
         os.remove(path)