The URL http://dev.mysql.com/doc/refman/5.0/en/savepoints.html is no longer available

activerecord/lib/active_record/transactions.rb

@@ -165,7 +165,7 @@ class TransactionError < ActiveRecordError # :nodoc:
     # writing, the only database that we're aware of that supports true nested
     # transactions, is MS-SQL. Because of this, Active Record emulates nested
     # transactions by using savepoints on MySQL and PostgreSQL. See
-    # http://dev.mysql.com/doc/refman/5.0/en/savepoints.html
+    # http://en.wikipedia.org/wiki/Savepoint
     # for more information about savepoints.
     #
     # === Callbacks