Developer credits
Git commits in Moodle 2.6.x by Jody Steele
commit add50b5ab0c237c951e6392e0e447e394c91f4f8 Author: Jody Steele <steelej@queensu.ca> Date: Wed, 16 Oct 2013 23:19:34 +0800 Tag: v2.6.0-rc1 MDL-38628 mod_assign: Allow a user to specify "No Grade" when grading an assignment submission