maximum recursion depth exceeded on Django model when creating

I have this strange problem with one of my Django models and I was able to fix it but don't understand what is happening.

These are the models:

class Player(models.Model):
    facebook_name = models.CharField(max_length=100)
    nickname = models.CharField(max_length=40, blank=True)

    def __unicode__(self):
        return self.nickname if self.nickname else self.facebook_name


class Team(models.Model):
    name = models.CharField(max_length=50, blank=True)
    players = models.ManyToManyField(Player)

    def __unicode__(self):
        name = '(' + self.name + ') ' if self.name else ''
        return name + ", ".join([unicode(player) for player in self.players.all()])

Whenever I make a new (empty) Team object and want to get players from it, I got a RuntimeError: maximum recursion depth exceeded. For example:

>>> team = Team()
>>> team.players
    Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/Users/walkman/Projects/fociadmin/venv/lib/python2.7/site-packages/django/db/models/fields/related.py", line 897, in __get__
    through=self.field.rel.through,
  File "/Users/walkman/Projects/fociadmin/venv/lib/python2.7/site-packages/django/db/models/fields/related.py", line 586, in __init__
    (instance, source_field_name))
  File "/Users/walkman/Projects/fociadmin/venv/lib/python2.7/site-packages/django/db/models/base.py", line 421, in __repr__
    u = six.text_type(self)
  File "/Users/walkman/Projects/fociadmin/fociadmin/models.py", line 69, in __unicode__
    return name + ", ".join([unicode(player) for player in self.players.all()])
  File "/Users/walkman/Projects/fociadmin/venv/lib/python2.7/site-packages/django/db/models/fields/related.py", line 897, in __get__
    through=self.field.rel.through,
  File "/Users/walkman/Projects/fociadmin/venv/lib/python2.7/site-packages/django/db/models/fields/related.py", line 586, in __init__
    (instance, source_field_name))
  File "/Users/walkman/Projects/fociadmin/venv/lib/python2.7/site-packages/django/db/models/base.py", line 421, in __repr__
    u = six.text_type(self)
  File "/Users/walkman/Projects/fociadmin/fociadmin/models.py", line 69, in __unicode__
    return name + ", ".join([unicode(player) for player in self.players.all()])
...

Why is this happening? I was able to fix it by checking for pk and only generate the name then, but what I think it should work the way is returning only the name because ", ".join... would be an empty list. Instead, some recursion occurs which I don't understand.