Log Message:
Changes 5.5.18:

Functionality Added or Changed
* Upgrading from an Advanced GPL RPM package to an Advanced RPM package did not
  work. Now on Linux it is possible to use rpm -U to replace any installed
  MySQL product by any other of the same release family. It is not necessary to
  remove the old produce with rpm -e first.

Bugs Fixed
* Incompatible Change: Replication.
* During the table-opening process, memory was allocated and later freed that
  was needed view loading, even for statements that did not use views. These
  unnecessary allocation and free operations are no longer done.
* mysql_plugin mishandled the --plugin-ini, --mysqld, and --my-print-defaults
  options under some circumstances.
* mysql_plugin returned the wrong error code from failed server bootstrap
  execution.
* Several improvements were made to the libedit library bundled with MySQL
  distributions, and that is available for all platforms that MySQL supports
  except Windows.
* ARCHIVE tables with NULL columns could cause server crashes or become corrupt
  under concurrent load.
* OPTIMIZE TABLE could corrupt MyISAM tables if myisam_use_mmap was enabled.
* A query that selected a GROUP_CONCAT() function result could return different
  values depending on whether an ORDER BY of the function result was present.
* For FEDERATED tables, loss of connection to the remote table during some
  insert operations could cause a server crash.