print message after backout that tells that backout adds new head.
Content-type: text/html
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US">
<head>
<link rel="icon" href="?static=hgicon.png" type="image/png">
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
<meta name="robots" content="index, nofollow"/>
<link rel="stylesheet" href="?static=style-gitweb.css" type="text/css" />