[interchange] prevent warning when label is undefined

[Stefan Hornburg]

commit 3766daf1adb2bb468e1c1efa0f12d3fe5dc87bcd
Author: Peter Ajamian <peter at pajamian.dhs.org>
Date:   Thu Apr 15 14:57:41 2010 +0200

    prevent warning when label is undefined

 lib/Vend/Interpolate.pm |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/lib/Vend/Interpolate.pm b/lib/Vend/Interpolate.pm
index d4e2a3b..9cdf751 100644
--- a/lib/Vend/Interpolate.pm
+++ b/lib/Vend/Interpolate.pm
@@ -4907,7 +4907,7 @@ sub tag_loop_list {
 			my @items = split /\s*,\s*/, $list;
 			for(@items) {
 				my ($o, $l) = split /=/, $_;
-				$l = $o unless $l =~ /\S/;
+				$l = $o unless defined $l && $l =~ /\S/;
 				push @rows, [ $o, $l ];
 			}
 		};