The current algorithm is to first attempt "LOCAL", and then "REMOTE".
The new strategy is to look at the host name, and if it appears local, try LOAD DATA LOCAL INFILE first. Conversely, if it appears to be remote, try LOCAL DATA INFILE first. Then fallback to the other case.
This fixes the issue reported by Monica/Anton on the forum. Windows Server 2008, php 5.3.2 --with-pdo-mysql=mysqlnd, adapter=PDO_MYSQL, MySql 5.1.45, and "local infile = on", Piwik_Exec('LOAD DATA LOCAL INFILE ...') throws an exception ($e->getMessage() is empty), and subsequent queries (ie fallback) all fail.