Typo in stale thread removal.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3731 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb

@@ -98,7 +98,7 @@ def remove_stale_cached_threads!(cache, &block)
           stale = Set.new(cache.keys)
 
           Thread.list.each do |thread|
-            stale -= t.object_id if t.alive?
+            stale -= thread.object_id if t.alive?
           end
 
           stale.each do |thread_id|