management_form generates field with '(' caracter
===

I have a strange glitch in django admin:

I've changed template a lot and all is working like a charm, except the tabular inline...

**telefone.py**

    class Telefone(models.Model):
        numero_telefone = models.CharField(max_length=20, verbose_name='número')
        tipo_telefone = models.ForeignKey(TipoTelefone, verbose_name='tipo')
        pessoa = models.ForeignKey(Pessoa)

        def __unicode__(self):
            return self.numero_telefone

        class Meta:
            app_label = 'academico'


**pessoa.py**

    TIPO_CHOICES = (
        ('F', 'Física'),
        ('J', 'Jurídica')
    )
    
    class Pessoa(models.Model):
        nome = models.CharField(max_length=45,)
        tipo = models.CharField(max_length=1, choices=TIPO_CHOICES)
        razao_social = models.CharField(max_length=45, null=True, blank=True)
        nascimento = models.DateField(null=True, blank=True)
        endereco = models.CharField(max_length=45, null=True, blank=True)
        numero_endereco = models.CharField(max_length=45, null=True, blank=True, verbose_name='número')
        complemento_endereco = models.CharField(max_length=45, null=True, blank=True, verbose_name='complemento')
        bairro = models.CharField(max_length=45, null=True, blank=True)
        cidade = models.ForeignKey(Cidade, null=True, blank=True)
        cep = models.CharField(max_length=9, null=True, blank=True)
        email = models.EmailField(null=True, blank=True)
        foto = models.FileField(upload_to='pessoas', null=True, blank=True)
    
        class Meta:
            app_label = 'academico'
    
        def __unicode__(self):
            return self.nome

**admin.py**

    class TelefoneInline(admin.TabularInline):
        model = Telefone

    class PessoaAdmin(admin.ModelAdmin):
        inlines = [TelefoneInline,]

    admin.site.register(Pessoa, PessoaAdmin)

In popup when submit the form returns the message: [u'ManagementForm data is missing or has been tampered with']

Checking html the management formdata contains the '(' character. 

    <input type="hidden" name="telefone_set-TOTAL_FORMS" value="(0" id="id_telefone_set-TOTAL_FORMS" autocomplete="off">
    <input type="hidden" name="telefone_set-INITIAL_FORMS" value="(0" id="id_telefone_set-INITIAL_FORMS">
    <input type="hidden" name="telefone_set-MAX_NUM_FORMS" id="id_telefone_set-MAX_NUM_FORMS" autocomplete="off">

What is causing this?