Django form initial value changes after save - django

Question

I use a custom form inherited from django's UserCreationForm to add user. How ever i have to set different initial value for username field.It works perfectly but after hitting save button the user get saved with a different username than the initial value shown in the form.You can find the code below
from django.contrib.auth.forms import UserCreationForm
class AdminUserCreationForm(UserCreationForm):
"""
AdminForm for creating an instance of custom USER_MODEL.
"""
email = forms.EmailField(required=True)
class Meta:
model = User
fields = ("username", "email")
field_classes = {'username': UsernameField}
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.initial['username'] = random_username_generator()
self.fields['username'].disabled = True
self.fields['password1'].required = False
self.fields['password2'].required = False
def clean_username(self):
username = self.cleaned_data['username'].lower()
try:
User.objects.get(username=username)
except User.DoesNotExist:
return username
raise forms.ValidationError('A user with username {} already exists'.format(username))
def clean_email(self):
email = self.cleaned_data['email'].lower()
try:
User.objects.get(email=email)
except User.DoesNotExist:
return email
raise forms.ValidationError('A user with email {} already exists'.format(email))
def save(self, commit=True):
import ipdb; ipdb.set_trace();
user = super(AdminUserCreationForm, self).save(commit=False)
# user = self.instance
qb = QuickBlox()
qb_password = reset_password_generator()
user.qb_password = qb_password + 'vx'
user.save()
attempt = LoginAttempts()
attempt.user = user
attempt.save()
send_invite_mail(user)
return user