[interchange] Fix bug in Cart.pm affecting prefixes on MaxQuantityField

[Jon Jensen]

commit 5659b76808ffbc8847881db017a54b8d905ba72e
Author: Josh Lavin <josh at perusion.com>
Date:   Mon May 2 11:34:39 2011 -0500

    Fix bug in Cart.pm affecting prefixes on MaxQuantityField

 lib/Vend/Cart.pm |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/lib/Vend/Cart.pm b/lib/Vend/Cart.pm
index 4eb01eb..6aebd92 100644
--- a/lib/Vend/Cart.pm
+++ b/lib/Vend/Cart.pm
@@ -262,8 +262,8 @@ sub toss_cart {
 				  $tab = $item->{mv_ib} || $Vend::Cfg->{ProductFiles}[0];
 			      }
 
-			      my ($prefix) = $tab =~ s/^([=\?])//;
-			      $prefix ||= '';
+			      my $prefix = '';
+			      $tab =~ s/^([=?])// and $prefix = $1;
 
 			      my $max = \$quantity_cache{"$tab.$col.$item->{code}"};
 			      $$max ||= ::tag_data($tab, $col, $item->{code});