Generated courses do not have valid start date, course reset updates module dates incorrectly

Steps to reproduce:

1. Login as an administrator make sure that debugging is set to DEVELOPER.
2. Go to Site administration ► Development ► Make test course
3. Choose "XS" for "Size of course" and enter a value for "Course short name".
4. Click on "Create a course"
5. On the created course's main page, select the auto-generated Assignment.
6. Edit the assignment's settings.
7. Enable the assignment's due date by setting the "Enable" check box for the "Due Date" row as checked.
8. Click on "Save and return to course"
9. Under the Course administration, click on "Reset".
10. For the "Course start date" row, set the Enable check box as checked.
11. Adjust the Course start date by 1 day.
12. Click on "Reset course"
13. Go back to the assignment and check its due date.

Expected Results:

1. The assignment's due date should have been adjusted by 1 day.

Actual Results:

1. The assignment's due date is adjusted by more than 45 years in the future.

• i.e. The original due date was 17/08/2015, the course start date is adjusted to 18/08/2015, the assignment's due date becomes 02/04/2061.

Other Notes:

• This issue only seems to occur on the auto-generated assignment. For manually created assignments, it seems that the due dates are being properly adjusted.