Hi,

This patch is required for url-http-ntlm.el to handle redirects.  I'd
like someone more familiar with url-http.el to review it.  Basically,
this patch leaves it up to the authentication scheme to decide whether
to include an "Authorization" across a redirect or not.

I tested this on normal redirects (independent of url-http-ntlm.el) and
it seems to work fine, with the built-in Basic authorization scheme
re-adding the header where required.

Thanks,
Thomas