Only change from 2.9 is the modification of the slasharguments
admin setting string to recommend always to keep the setting enabled
and fix the problem in the server, warning about the drawbacks
of disabling it.
Also, there is a little phpdoc note added to one custom check
to have clearly specified when we can get rid of it.
The sequence of questions that made up a quiz used to be stored as a
comma-separated list in quiz.questions. Now the same information is
stored in the rows in the quiz_slots table. This is not just 'better' in
a database design sense, but it allows for the future changes we will
need as we enhance the quiz in the MDL-40987 epic.
Having changed the database structure, all the rest of the code needs to
be changed to account for it, and that is done here.
Note that there are not many unit tests for the changed bit. That is
because as part of MDL-40987 we will be changing the code further, and
we will add unit tests then.
This data should all have been upgraded when moving to Moodle 2.1. It
was only kept as a back-up, and now, after 3 years have past, we can
clean it up.
In Moodle 2.1, there was a major DB upgrade relating to questions, and
it was possible to delay some of that upgrade. Now, those DB tables are
changing again, and the time has come to insist that all the updata has
been upgraded (or deleted).
1. So we will truncate the question summary to 65000 chars if necessary.
2. Also, fix one minor error in mutlianswer save_question_options.
question_bank::MAX_SUMMARY_LENGTH is not the most logical class to add
the constant to, but it needs to be accessible during upgrade, so I was
lazy and put it there.
There was one place where I had only fixed the backup code to work-around bad data from Moodle 2.0. I needed to make the equivalent change in the upgrade code.
The bad data is that the seq_number fields can be wrong (not unique). Se already have data ordered by (seq_number, id) and the array keys of the array we are building are not used for anything, so this fix deals with the problem.
