Description:

The ServerTokens directive currently can at best be set to Prod, which will
cause apache to return "Apache" as Server header. Some problem still occurs:

First, the level of security by obscurity of this directive is not acceptable
by some people that just want to change it to some other value, without
re-compiling Apache, or people that even want to simply drop the "Server: "
header. Secondly, if apache is configured as a reverse proxy, and a malformed
request is received, then it will display its own server token instead of the
backend one, so we need to handle error response header.

I developed this tiny module by hijacking normal behavior of (reverse) proxy
feature of Apache : i.e. even if a request is not a proxy request, I tag it as
if it was, to make Apache core let me do what I want with this header.