Merge branch '3.1-stable' into develop

Conflicts resolved:
	system/database/drivers/sqlite/sqlite_driver.php
	system/database/drivers/sqlite/sqlite_forge.php
	system/database/drivers/sqlite/sqlite_result.php
	system/database/drivers/sqlite/sqlite_utility.php
	system/helpers/captcha_helper.php
	system/helpers/email_helper.php
	system/helpers/inflector_helper.php
	system/helpers/smiley_helper.php
	system/language/english/form_validation_lang.php
	system/libraries/Cart.php
	system/libraries/Form_validation.php
	system/libraries/Javascript.php
	system/libraries/Javascript/Jquery.php
	system/libraries/Session/SessionHandlerInterface.php
	tests/codeigniter/helpers/inflector_helper_test.php
	user_guide_src/source/helpers/inflector_helper.rst

1 files changed, 1 insertions, 1 deletions

diff --git a/system/database/drivers/postgre/postgre_forge.php b/system/database/drivers/postgre/postgre_forge.php
index 418376ab4..353ddac99 100644
--- a/system/database/drivers/postgre/postgre_forge.php
+++ b/system/database/drivers/postgre/postgre_forge.php
@@ -131,7 +131,7 @@ class CI_DB_postgre_forge extends CI_DB_forge {
 			if (isset($field[$i]['null']))
 			{
 				$sqls[] = $sql.' ALTER COLUMN '.$this->db->escape_identifiers($field[$i]['name'])
-					.($field[$i]['null'] === TRUE ? ' DROP NOT NULL' : ' SET NOT NULL');
+					.(trim($field[$i]['null']) === $this->_null ? ' DROP NOT NULL' : ' SET NOT NULL');
 			}
 
 			if ( ! empty($field[$i]['new_name']))