Can't include a HEREDOC within RHS of a Regex

[wind]

Howdy Fellow Monks,

I recently attempted to include a heredoc within the eval'd rhs of a regex. No matter what I attempted, perl died with the following error:

Can't find string terminator "END_TEXT" anywhere before EOF

I've reduced this code to the following example:

use strict;
use warnings;

my $data = "line1\nfoobar\nline3\n";

$data =~ s{(foo)(bar)}{
    my $one = $1;
    my $two = $2;

    $one .= <<'END_TEXT';
Insert 1
Insert 2
END_TEXT

    $one.$two;
}e;

print $data;

Obviously, one can "fix" the issue by using an ordinary string instead, but I would like y'alls advice concerning this.

Super searching revealed only one thread connected to both heredoc's and regex, but it was unrelated.

Thanks

Update: Anon monk pointed out that it does work when outside of the RHS of the regex:

$data =~ s{(foo)(bar)}{
    my $one = $1;
    my $two = $2;

    $one .= <<'END_TEXT';

    $one.$two;
}e;
Insert 1
Insert 2
END_TEXT