From: Tara L Andrews <tla@mit.edu>
Date: Fri, 24 Feb 2012 01:11:05 +0000 (+0100)
Subject: fix change detection bug
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=7c293912d5aeee653131449d246a0f442dc8119f;p=scpubgit%2Fstemmatology.git

fix change detection bug
---

diff --git a/lib/Text/Tradition/Collation.pm b/lib/Text/Tradition/Collation.pm
index 9ec858e..69b1a59 100644
--- a/lib/Text/Tradition/Collation.pm
+++ b/lib/Text/Tradition/Collation.pm
@@ -1366,7 +1366,8 @@ sub calculate_ranks {
     # Do we need to invalidate the cached data?
     if( $self->has_cached_svg || $self->has_cached_table ) {
     	foreach my $r ( $self->readings ) {
-    		next if $existing_ranks{$r} && $existing_ranks{$r} == $r->rank;
+    		next if defined( $existing_ranks{$r} ) 
+    			&& $existing_ranks{$r} == $r->rank;
     		# Something has changed, so clear the cache
     		$self->_clear_cache;
 			# ...and recalculate the common readings.