AP_REQUEST_DONE is bogus and a bad idea. This had the http_header filter return -3 for every HEAD request, which in turn made us call ap_die. Of course, if we didn't have a 200 status (say we had a 206), then we would seg fault, because we would end up sending down a second EOS bucket, which would in turn make us call the byterange filter again, but at this point, we hadn't cleaned up the byterange ctx structure, because it was never supposed to be called again.
This was biting us on apache.org, where we had a HEAD request for bytes=100- for a file. This was a major seg fault. We are better off just returning OK is much safer.