I am on the bleeding edge and using the master branch of Org-mode. After updating the source of Org a few days ago, I found the easy template can be expanded by TAB key now, that is:
When I press TAB after typing <s in an Org file, nothing happens.
Version Info:GNU Emacs 25.2.2 (x86_64-pc-linux-gnu, GTK+ Version 3.22.28) of 2018-02-19, modified by DebianOrg mode version 9.0.5 (release_9.0.5-86-ga91eae @ /home/kdr2/Work/opensrc/org-mode/lisp/)
Does anybody know what's wrong about this? Thanks.
 Greetings.

ZHUO QL (KDr2, http://kdr2.com)