You're setting $SIG{CHLD} yourself so the wait() implicit in the backticks command will report there are no children.

Set $SIG{CHLD} to undef before the foreach loop to see that that fixes the problem.

update: 

$|=1;
my $ret1 = `date`;
my $exit1 = $?;
print STDERR "exit1=$exit1 ret1=$ret1";

$SIG{CHLD} = sub {print "Sigchld\n";wait};


foreach my $i (1..5) {
    my $ret2 = `date`;
    my $exit2 = $?;
    print STDERR "exit2=$exit2 ret2=$ret2";
}

[download]
output: 
exit1=0 ret1=Wed Jun 20 22:29:13 CEST 2007
Sigchld
exit2=-1 ret2=Wed Jun 20 22:29:13 CEST 2007
Sigchld
exit2=-1 ret2=Wed Jun 20 22:29:13 CEST 2007
Sigchld
exit2=-1 ret2=Wed Jun 20 22:29:13 CEST 2007
Sigchld
exit2=-1 ret2=Wed Jun 20 22:29:13 CEST 2007
Sigchld
exit2=-1 ret2=Wed Jun 20 22:29:13 CEST 2007

[download]
"What should it profit a man, if he should win a flame war, yet lose his cool?"

In reply to Re^3: $? stuck returning -1... by Joost
in thread $? stuck returning -1... by cmv

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