Django tests failing with PostgreSQL database backend

Can someone confirm that the _mixer_ test suite does not pass all of the Django backend tests?

I'm currently having trouble getting all my project's tests to pass since switching the test database backend from SQLite to Postgres and discovered that _mixer_ seems to have issues with certain field type validations (i.e. max-length restrictions, smallint out of range etc...).

> Results (30.89s):
48 passed
13 failed
- tests/test_django.py:31 test_fields
- tests/test_django.py:76 test_custom
- tests/test_django.py:116 test_select
- tests/test_django.py:130 test_relation
- tests/test_django.py:191 test_random
- tests/test_django.py:200 test_mix
- tests/test_django.py:223 test_contrib
- tests/test_django.py:255 test_skip
- tests/test_django.py:261 test_generic
- tests/test_django.py:274 test_deffered
- tests/test_django.py:291 test_guard
- tests/test_django.py:298 test_reload
- tests/test_django.py:310 test_small_positive_integer_field_not_too_large
2 skipped

Tried running the tests with current _mixer_ `master` branch and the following package versions:

```
Django==1.10.5
psycopg2==2.6.2
pytest==3.0.5
```

---
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Start by reproducing the failures in tests/test_django.py using Django 1.10.5, psycopg2 2.6.2, pytest 3.0.5, and a PostgreSQL test database. Compare the failing field, relation, and fixture cases with the SQLite results, then verify that the listed tests pass and constraints such as max length and small-integer ranges work correctly.

Written by the indexing model from the issue text.