Can not change value in DateTimeField in Admin when default is set

[Nikolay]

In our project I have model like with set "default":

from django.db import models
from django.utils import timezone


class DateModel(models.Model):
    dt = models.DateTimeField(default=timezone.now)
    date = models.DateField(default=timezone.now)
    tm = models.TimeField(default=timezone.now)

In admin interface on model page I edit values in all fields and then press "Save" or "Save or continue editing". Changes to DateTime field are not saved to database. Values in DateField and TimeField are saved.

This bug appeared in Django 1.10.1. In Django 1.10 all values were saved.

There is demo project demonstrating this behaviour in attachment (requires "Django==1.10.1" only).

[Tim Graham]

Duplicate of #27186