Using moodle 1.9.

1- As Admin,
a. create a new role called CanCreateSystemQuestions with Allowed permissions: moodle/question:add; moodle/question:editmine.
b. create a new role called CanUseSystemQuestions with Allowed permission: moodle/question:useall
Assign these 2 roles to all teachers on your moodle site.

2- Log in as teacher A
a. create question "Question A" in System default and save it.
b. try to edit "Question A" : you can click the Edit icon, you see the Edit question screen which says:
You have permission to :
    * Edit this question
    * Save this as a new question
Edit your question and click on the Save changes to save it in the same (System) category. You see an error message:
Sorry, but you do not currently have permissions to do that (move).

There seems to be a contradiction of "permissions" somewhere...

Joseph

PS.-- Clicking on the "More information about this error link" takes me to the http://docs.moodle.org/en/error/moodle/nopermissions page which informs me that "If you believe that your roles for that user DO allow that action you were attempting, then you may have found a bug. Congratulations!" Hence this bug report...