Strange Perl pattern matching

[Julien ÉLIE]

Hi,

There is something weird in what I obtain from Perl (5.8.8 and 5.10.0):

$ngname = 'trigofacile.test';
$newsgrouppats = '^trigofacile\..*$';
$exclusionpats = '^a\..*$';
$droppats = '';


If I try in control/modules/checkgroups.pl:

    #next if ($ngname !~ /$newsgrouppats/);
    print "A\n";
    next if ($ngname =~ /$exclusionpats/);
    print "B\n";
    next if ($ngname =~ /$droppats/);
    print "C\n";

Sat Jul  4 11:02:11 2009: control_checkgroups, ^trigofacile\..*$ test test b-checkgroups, ^a\..*$, , utf-8, , mail, 1
A
B
C


"C" should not have been written ($droppats is an empty string, so the condition
is true).
But if I uncomment the first line:

    next if ($ngname !~ /$newsgrouppats/);
    print "A\n";
    next if ($ngname =~ /$exclusionpats/);
    print "B\n";
    next if ($ngname =~ /$droppats/);
    print "C\n";


Sat Jul  4 11:02:35 2009: control_checkgroups, ^trigofacile\..*$ test test b-checkgroups, ^a\..*$, , utf-8, , mail, 1
A
B

It now works...


And the following is fine:

    next if ($ngname !~ /$newsgrouppats/);
    print "A\n";
    next if ($exclusionpats and $ngname =~ /$exclusionpats/);
    print "B\n";
    next if ($droppats and $ngname =~ /$droppats/);
    print "C\n";


Sat Jul  4 11:03:27 2009: control_checkgroups, ^trigofacile\..*$ test test b-checkgroups, ^a\..*$, , utf-8, , mail, 1
A
B
C



Does someone understand what is going on for the first case?
I cannot reproduce it in a standalone Perl script.  Only in controlchan :-/


P.-S.: The same goes on Hope too:

2:25 iulius at hope ~/test-install/bin% echo "control/b-checkgroups" | ./controlchan
Sat Jul  4 02:25:51 2009: starting
Sat Jul  4 02:25:51 2009: control_checkgroups, ^trigofacile\..*$ test test control/b-checkgroups, ^a\..*$, , utf-8, , log, 1
A
B
C


-- 
Julien ÉLIE

« Les amis de la vérité sont ceux qui la cherchent,
  et non ceux qui se vantent de l'avoir trouvée. » (Condorcet)