Merge pull request #4719 from owncloud/port_4701_master

Always check variable type before using readdir to avoid surprises

diff --cc apps/files_encryption/lib/util.php
Simple merge

diff --cc apps/files_external/lib/irods.php
Simple merge

diff --cc apps/files_trashbin/index.php
Simple merge

diff --cc lib/files/view.php
Simple merge

diff --cc lib/helper.php
Simple merge