Pass arguments given to `Message->headers` to `Message->content->headers`

[krauro]

the headers attribute on Mojo::Message is currently defined as

mojo/lib/Mojo/Message.pm

Line 126 in 19fc4f1

sub headers { shift->content->headers }

Which has the effect of ignoring any arguments passed to headers.
Is this intentional? The docs mention that message->headers is the same as message->content->headers

Reproducer:

use Mojo::UserAgent;
use Mojo::Headers;
use Data::Dumper;

my $ua  = Mojo::UserAgent->new;
my $tx = $ua->build_tx("GET" => "example.com");

my $new_headers = Mojo::Headers->new;
$new_headers->accept_encoding("br");
$new_headers->user_agent("req->headers");

$tx->req->headers($new_headers);
print Dumper($tx->req->headers); # Notice headers not updated

$new_headers = Mojo::Headers->new;
$new_headers->accept_encoding("br");
$new_headers->user_agent("req->content->headers");

$tx->req->content->headers($new_headers);
print Dumper($tx->req->content->headers);

Actual Output:

$VAR1 = bless( {
                 'headers' => {
                                'accept-encoding' => [
                                                       'gzip'
                                                     ],
                                'user-agent' => [
                                                  'Mojolicious (Perl)'
                                                ]
                              }
               }, 'Mojo::Headers' );
$VAR1 = bless( {
                 'headers' => {
                                'accept-encoding' => [
                                                       'br'
                                                     ],
                                'user-agent' => [
                                                  'req->content->headers'
                                                ]
                              }
               }, 'Mojo::Headers' );

Expected Output:

$VAR1 = bless( {
                 'headers' => {
                                'accept-encoding' => [
                                                       'br'
                                                     ],
                                'user-agent' => [
                                                  'req->headers'
                                                ]
                              }
               }, 'Mojo::Headers' );
$VAR1 = bless( {
                 'headers' => {
                                'accept-encoding' => [
                                                       'br'
                                                     ],
                                'user-agent' => [
                                                  'req->content->headers'
                                                ]
                              }
               }, 'Mojo::Headers' );

If this behaviour is not intentional, then maybe headers should be defined as follows

sub headers { shift->content->headers(@_) }