my $q_meta = quotemeta($q);
          my $tmp_test = ($page_title =~ /$q_meta/i) || 0;
          if (!$tmp_test) {

              my $tmp_test2 = lc $page_title eq lc $q;
              $is_exit = 1 if $tmp_test2;

              my $tmp_test3 = is_utf8($page_title);
              my $tmp_test4 = is_utf8($q);

              # For debugging.
              if ($is_dilbert) {
                  warn qq(\nDILBERT 1a\t$page_title\t$q_meta\t$tmp_tes
+t\t$tmp_test2\t$tmp_test3\t$tmp_test4\n") if \
$is_dilbert;
              }
[download]

produces DILBERT 1a      Polygram compilation albums     Polygram\ compilation\ albums   0       1       1       1

So whats $q? $page_title? This is the important part, the bytes that go into these values, its probably invisible whitespace or nonbreaking whitespace that is tripping you up (they just look like whitspace, but are different bytes)

That's neither values for $test and $test2, nor a stand alone piece of code.

I'll just give up on you.

#!perl -w
use strict;
my $test = 'foo[bar]';
my $test2 = $test;
print $test eq $test2 ? "'$test' is equal to itself\n" : "'$test' is n
+ot equal to itself\n";
print $test =~ /$test2/ ? "'$test' does match itself\n" : "'$test' doe
+s not match itself\n";

__END__

> perl -w tmp.pl
'foo[bar]' is equal to itself
'foo[bar]' does not match itself
[download]

Also see quotemeta and/or \Q..\E.