This is a followup of
1) For MOODLE_30_STABLE and earlier, empty section names are being stored as NULL in the database. That null means "use default name".
MDL-53071 it was detected that for master (3.1.dev) we have changed that behavior to store empty strings instead. Both when using the form and also when performing inline section name edition.
So this issue is about:
A) Move back, in master, to store NULLs in database. It's not really super-critical, but better if we keep the historic meaning there. Both using the form and inline editing.
B) Ideally cover with some tests all these cases (1-space, empty, zero...), so we keep them constant over the time (in fact
MDL-53071 was a regression).
That's it, ciao