Ordering via foreign key causes multiple display of entries in Admin view

[andreas]

Ordering via foreign key causes multiple display of entries in Admin view.

For instance:

class ParentClass(meta.Model):
    somevar        = meta.CharField(maxlength=100)
    def __repr__(self):
        return self.somevar
    class META:
        admin      = meta.Admin()
        ordering   = ['somevar']
 
class FirstChild(meta.Model):
    theparent      = meta.ForeignKey(ParentClass)
    myvar          = meta.CharField(maxlength=100)
    def __repr__(self):
        return repr(self.get_theparent()) + "-" + self.myvar
    class META:
        admin      = meta.Admin()
        ordering   = ['theparent']

After entering two ParentClasses, parent1 and parent2, and two FirstChilds of parent1, child1 and child2, the Admin "First childs" view looks like this:

First child 
parent1-child2 
parent1-child1 
parent1-child2 
parent1-child1

2 first childs

Workaround: Add list_display-option:

class FirstChild(meta.Model):
    ...
    class META:
        admin      = meta.Admin(list_display = ('myvar', 'theparent'))
        ordering   = ['theparent']