Refs #6930, make minimum_required_piwik default in travis.yml generator, not latest_stable.

plugins/TestRunner/TravisYml/Generator/PluginTravisYmlGenerator.php

@@ -70,13 +70,13 @@ class PluginTravisYmlGenerator extends Generator
             $testsToRun[] = array('name' => 'PluginTests',
                 'vars' => "MYSQL_ADAPTER=PDO_MYSQL");
             $testsToRun[] = array('name' => 'PluginTests',
-                'vars' => "MYSQL_ADAPTER=PDO_MYSQL TEST_AGAINST_CORE=latest_stable");
+                'vars' => "MYSQL_ADAPTER=PDO_MYSQL TEST_AGAINST_CORE=minimum_required_piwik");
 
             $testsToExclude[] = array('description' => 'execute latest stable tests only w/ PHP 5.5',
                 'php' => '5.3.3',
-                'env' => 'TEST_SUITE=PluginTests MYSQL_ADAPTER=PDO_MYSQL TEST_AGAINST_CORE=latest_stable');
+                'env' => 'TEST_SUITE=PluginTests MYSQL_ADAPTER=PDO_MYSQL TEST_AGAINST_CORE=minimum_required_piwik');
             $testsToExclude[] = array('php' => '5.4',
-                'env' => 'TEST_SUITE=PluginTests MYSQL_ADAPTER=PDO_MYSQL TEST_AGAINST_CORE=latest_stable');
+                'env' => 'TEST_SUITE=PluginTests MYSQL_ADAPTER=PDO_MYSQL TEST_AGAINST_CORE=minimum_required_piwik');
         }
 
         if ($this->isTargetPluginContainsUITests()) {