Merge branch '3.1-stable' into develop

Conflicts resolved:
	.travis.yml
	system/core/CodeIgniter.php
	system/database/drivers/oci8/oci8_forge.php
	system/database/drivers/pdo/subdrivers/pdo_oci_forge.php
	system/helpers/path_helper.php
	system/libraries/Email.php
	user_guide_src/source/changelog.rst
	user_guide_src/source/conf.py
	user_guide_src/source/contributing/index.rst
	user_guide_src/source/general/requirements.rst
	user_guide_src/source/general/styleguide.rst
	user_guide_src/source/installation/downloads.rst
	user_guide_src/source/installation/upgrade_310.rst
	user_guide_src/source/installation/upgrading.rst

1 files changed, 1 insertions, 0 deletions

diff --git a/system/libraries/Session/Session.php b/system/libraries/Session/Session.php
index dde84a775..3b391a8ef 100644
--- a/system/libraries/Session/Session.php
+++ b/system/libraries/Session/Session.php
@@ -91,6 +91,7 @@ class CI_Session {
 		// Note: BC workaround
 		elseif (config_item('sess_use_database'))
 		{
+			log_message('debug', 'Session: "sess_driver" is empty; using BC fallback to "sess_use_database".');
 			$this->_driver = 'database';
 		}