by Juan Leyva.
You can find the first version of the backport here:
https://github.com/cvaconsulting/moodle-mod_assign
Notice that if you use this module in your 2.2 installation you must upgrade directly to 2.4 or above
If you want to use this module in 2.1 you should edit all the version.php files and include the correct required version
Regards