Are you sure? If I'm understanding your comment, the only scenario where this should be true is if your fork is failing. What happens when you run this code:

use strict;
use warnings;

my $pid = fork();
die "Fork failed" if not defined $pid;
if ($pid) { #parent
    print "Parent output\n";
} else { #child
    exec q|perl -e 'sleep(1); print "Child output\n"'|;
}
wait;
print "Parent finishing\n";
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