Same links at different ListNodes which are under same class creates problem #5451

[zetaopsbot]

class SinavYerleri(ListNode):
        room = Room('Sınav Yeri')

class Ogrenciler(ListNode):
        ogrenci = Ogrenci('Öğrenci')
        room = Room('Sınav Yeri')

SinavYerleri and Ogrenciler ListNodes has a same Room link and for example when adding a new room to SinavYerleri listnode, at the same time same room is being added to Ogrenciler listnode's room field. Like this:

In [11]: r = Room.objects.filter()[0]
In [12]: s = SinavEtkinligi()
In [13]: s.SinavYerleri
Out[13]: []
In [14]: s.Ogrenciler
Out[14]: []
In [15]: s.SinavYerleri(room = r)
Out[15]: <SinavYerleri: SinavYerleri object>
In [16]: s.save()
Out[16]: None None Henüz zamanlanmadi
In [17]: s.SinavYerleri
Out[17]: [<SinavYerleri: SinavYerleri object>]
In [18]: s.Ogrenciler
Out[18]: [<Ogrenciler: Ogrenciler object>]

pyoko