/usr/share/perl5/Text/Trac/Heading.pm is in libtext-trac-perl 0.16-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | package Text::Trac::Heading;
use strict;
use base qw(Text::Trac::BlockNode);
our $VERSION = '0.16';
sub init {
    my $self = shift;
    $self->pattern(qr/^(=+) \s (.*) \s (=+)$/xms);
}
sub parse {
    my ( $self, $l ) = @_;
    my $c = $self->context;
    $l =~ $self->pattern or return;
    my $level = length($1) + $c->min_heading_level -1;
    my $id = $self->_strip( $2 );
    $l = qq(<h$level id="$id">) .  $self->replace($2) . qq(</h$level>);
    $c->htmllines($l);
}
sub _strip {
  my ( $self, $word ) = @_;
  $word =~ s/[\s,_`'{}!]//g;
  return $word;
}
1;
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