Without this change we get a wrong $pfxlen value and the check_export_ok()
checks with with a wrong directory name. Without this patch the below
$projects_list fails with gitweb

$projects_list = "/tmp/a/b/";
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@gmail.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>