[ic] Bugfix for Cart.pm, MaxQuantityField prefix

[Josh Lavin]

I discovered a bug in Cart.pm, when using prefixes in MaxQuantity field.

A setting such as:

     MaxQuantityField  inventory:quantity, ?inventory:max_order

would not work as expected according to the docs, but would ignore the 
prefix, and add the columns.

The patch is simple (the problem is the substitution caused prefix to be 
set to a '1', not the actual prefix):

-      my ($prefix) = $tab =~ s/^([=\?])//;
-      $prefix ||= '';
+      $tab =~ s/^([=\?])//;
+      my $prefix = $1 || '';

https://github.com/jlavin/interchange/commit/2f277d9d209205e1746b5f92b90ee0015361360c

-- 
Josh Lavin
Perusion -- Expert Interchange Consulting    http://www.perusion.com/