Exception on retrieving geometry data in Rails 3.1

[dazuma]

This issue is just to track an external issue, seemingly a bug in the mysql gem.

Under Rails 3.1, any operation that retrieves geometry data fails with an exception:
ActiveRecord::StatementInvalid: TypeError: unknown buffer_type: 255

This happens because the mysql gem (as of version 2.8.1), in the binary protocol used by prepared statements, does not recognize the MYSQL_TYPE_GEOMETRY buffer type for return values.