I ended up just making my own verison of file_md5_hex that I was using:

sub file_md5_hex_1m {
    my ($file,$bn,$ut)   = @_;
    my $fh         = $getfh->($file) or return;
    
    my $cnt = 0;
    my $md5 = Digest::MD5->new();
    my $buf;
    while(my $l = read($fh, $buf, 1024)) {
        $md5->add( $buf );
        $cnt++;
        if ($cnt == 1024) {last;}
    }
    return $md5->hexdigest;
}
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