mysql.rb ignores IOError in finalizer when socket is already closed

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6241 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/vendor/mysql.rb

@@ -1174,7 +1174,11 @@ def real_connect(*args)
   def finalizer(net)
     proc {
       net.clear
-      net.write Mysql::COM_QUIT.chr
+      begin
+        net.write(Mysql::COM_QUIT.chr)
+        net.close
+      rescue  # Ignore IOError if socket is already closed.
+      end
     }
   end