Sorry for my late reply.
It is a university in the Netherlands.
I tried to double-check, but i can't find the exact rules anymore.
I do remember it specifically, because i wanted to put code written during my master's thesis online but had to ask permission from the university.
I guess you can compare it to doing graduation work within a company, the company owns the work the student does. The same i guess holds for the university.
This is probably not the case. At my University they own the rights to all code that is written as part of the educational program, not the students.
The decision doesn't have to be logical; it was unanimous.