don't consider Content-Location when determining the base URI GH#51

RFC 7231 says:
 The definition of Content-Location has been changed to no longer
 affect the base URI for resolving relative URI references, due to
 poor implementation support and the undesirable effect of potentially
 breaking relative links in content-negotiated resources.
This change was originally suggested by Toby Inkster in 2012.

Author: neilb

Changes

@@ -1,6 +1,8 @@
 Revision history for HTTP-Message
 
 {{$NEXT}}
+    - We now don't consider the Content-Location header when asked
+      for the base URI. RFC 7231 says we shouldn't. (GH#51) (Neil Bowers)
 
 6.40      2022-10-12 15:45:52Z
     - Fixed two typos in the doc, originally reported by FatherC

lib/HTTP/Response.pm

@@ -84,7 +84,6 @@ sub base
     my $self = shift;
     my $base = (
 	$self->header('Content-Base'),        # used to be HTTP/1.1
-	$self->header('Content-Location'),    # HTTP/1.1
 	$self->header('Base'),                # HTTP/1.0
     )[0];
     if ($base && $base =~ /^$URI::scheme_re:/o) {
@@ -475,7 +474,7 @@ in HTML documents.
 
 =item 2.
 
-A "Content-Base:" or a "Content-Location:" header in the response.
+A "Content-Base:" header in the response.
 
 For backwards compatibility with older HTTP implementations we will
 also look for the "Base:" header.
@@ -490,6 +489,13 @@ received some redirect responses first.
 
 If none of these sources provide an absolute URI, undef is returned.
 
+B<Note>: previous versions of HTTP::Response would also consider
+a "Content-Location:" header,
+as L<RFC 2616|https://www.rfc-editor.org/rfc/rfc2616> said it should be.
+But this was never widely implemented by browsers,
+and now L<RFC 7231|https://www.rfc-editor.org/rfc/rfc7231>
+says it should no longer be considered.
+
 When the LWP protocol modules produce the HTTP::Response object, then any base
 URI embedded in the document (step 1) will already have initialized the
 "Content-Base:" header. (See L<LWP::UserAgent/parse_head>).  This means that

t/response.t

@@ -105,7 +105,7 @@ for ($r->redirects) {
 
 is($r->base, $r->request->uri);
 $r->push_header("Content-Location", "/1/A/a");
-is($r->base, "http://www.sn.no/1/A/a");
+is($r->base, $r->request->uri); # we no longer consider Content-Location
 $r->push_header("Content-Base", "/2/;a=/foo/bar");
 is($r->base, "http://www.sn.no/2/;a=/foo/bar");
 $r->push_header("Content-Base", "/3/");