It seems like this was incorporated by

Bugs that were assigned to Marc. Changing assignee from Marc to Jackie.

This will not be worked on for 2.4 and probably won't make 2.5, either.

An excerpt from Diana Perpich's comment on (Assignments Option for Automatically Accepting Resubmissions), which touches on the null versus zero distinction when a student fails to submit their work:

"...Will the instructor be mad at "the system" for making her page through blank submissions? We've got instructors who post optional assignments. Would the system auto-submit these as well? How does the Gradebook currently import null submissions? Zeros? Making the instructor go back and seek out auto-submitted work and treat it differently will create a whole new set of support issues."

Hi, Marc. Gradebook doesn't actively poll Samigo to see if it has any scores to deliver. Instead, Samigo uses Gradebook services to create and manage "external assessments" in Gradebook. These external assessments in the Gradebook have null values per student initially. Any score then sent over for a particular student via the updateExternal service replaces the null.

In addition, Gradebook has a concept of Course Grade. It gets generated in Gradebook when the instructor clicks on the Course Grade button. For the sake of calculating a course grade, a null value won't due. So any uncompleted external assessment gets a value of zero for the sake of calculation. Same thing for any other assignments (i.e., those not externally managed) in Gradebook at that moment. From the Gradebook Help:

1. Click Course Grade below the listed assignments. You will see a list of all the students in the Gradebook. For each student, the points earned, the letter
   grade, and a percentage will be displayed. The letter grade and percentage are based on the total points available for the entire course. A zero is assigned
   automatically to all assignments that have not yet been completed.

Anyway, that's my understanding. I'll let the Gradebook Founding Fathers [Oliver, you there?] chime in with all the wherefore's and therefore's and address Peter's interesting observations.