Django + Postgres: Why is there a "database connection isn't set to UTC" error?

Question

PostgreSQL

settings.py

TIME_ZONE = 'Asia/Yekaterinburg'
USE_TZ = True

$ cat /etc/timezone 
Asia/Yekaterinburg
$ ll /etc/localtime 
/etc/localtime -> /usr/share/zoneinfo/Asia/Yekaterinburg

File "/home/user/myproject/apps/core/dev.py", line 22, in fill_dev_db
    list(Offer.objects.all())
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/models/query.py", line 256, in __iter__
    self._fetch_all()
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/models/query.py", line 1087, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/models/query.py", line 65, in __iter__
    for row in compiler.results_iter(results):
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 792, in results_iter
    for rows in results:
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 1238, in cursor_iter
    sentinel):
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 1237, in <lambda>
    for rows in iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)),
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/utils.py", line 101, in inner
    return func(*args, **kwargs)
  File "/home/user/myproject/python3/lib/python3.5/site-packages/django/db/backends/postgresql/utils.py", line 6, in utc_tzinfo_factory
    raise AssertionError("database connection isn't set to UTC")

An exception is generated from this function, but grep or backtrace did not give an answer from where it is called.

# django/db/backends/postgresql/utils.py
def utc_tzinfo_factory(offset):
    if offset != 0:
        raise AssertionError("database connection isn't set to UTC")
    return utc

Django 1.10.1
Ubuntu 16.04
Postgres 9.5.4
UPDATE:
Similar version of postgres is not playable in docker.
In vagrant installed a similar version of ubuntu and postgres - not reproducible.
On my Ubuntu 14.04 / Postgres 9.3 machine - not playable.
On that wheelbarrow it is stable under different accounts, I tried to reinstall postgres - it did not help. If the application remotely connects to this postgres, it will also reproduce.