DatabaseSelectTestCase.testSimpleComment is naive

DatabaseSelectTestCase.testSimpleComment tries to assert that the result of a dynamic query is exactly a litteral chain.

$expected = "/* Testing query comments */ SELECT test.name AS name, test.age AS age\nFROM \n{test} test";
$this->assertEqual($query, $expected, t('The flattened query contains the comment string.'));

Each database driver can override the Select query builder, so we should not test something literally like this.