[interchange] Fix handling of extra_query_params in Business::OnlinePayment wrapper.

[Stefan Hornburg]

commit f22c5ab730e0df7849e9a04488674e72a5faaeff
Author: Stefan Hornburg (Racke) <racke at linuxia.de>
Date:   Mon May 14 12:21:43 2012 +0200

    Fix handling of extra_query_params in Business::OnlinePayment wrapper.

 lib/Vend/Payment/BusinessOnlinePayment.pm |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/lib/Vend/Payment/BusinessOnlinePayment.pm b/lib/Vend/Payment/BusinessOnlinePayment.pm
index f875ba2..0c6952b 100644
--- a/lib/Vend/Payment/BusinessOnlinePayment.pm
+++ b/lib/Vend/Payment/BusinessOnlinePayment.pm
@@ -299,7 +299,7 @@ C<our_param>.
   my @extra = split /[\s,\0]+/, $opt->{extra_query_params};
   for (@extra) {
       my ( $k, $v ) = split /=/, $_;
-      $k ||= $v;
+      $v ||= $k;
       $params{$k} = $opt->{$v} || charge_param($v);
   }