Index: 051_fix_canonical_server_url.rb
===================================================================
--- 051_fix_canonical_server_url.rb     (revision 1266)
+++ 051_fix_canonical_server_url.rb     (working copy)
@@ -6,7 +6,7 @@
   def self.up
     unless $schema_generator
       b = Blog.find(1)
-      b.settings['canonical_server_url'] = b.settings['canonical_server_url'].gsub(%r{/$},'')
+      b.settings['canonical_server_url'] = b.settings['canonical_server_url'].gsub(%r{/$},'') unless b.settings['canonical_server_url'].nil?
       b.save
     end
   end