I am trying to upgrade my django project from `django1.8.8` to `django1.9.2`
Right now I encounter a problem when running my tests with `django1.9.2`:

```
python manage.py test

```

This gives me the following error

```
Traceback (most recent call last):
  File "manage.py", line 11, in <module>
    execute_from_command_line(sys.argv)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
    utility.execute()
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/__init__.py", line 345, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/commands/test.py", line 30, in run_from_argv
    super(Command, self).run_from_argv(argv)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/base.py", line 348, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/commands/test.py", line 74, in execute
    super(Command, self).execute(*args, **options)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/commands/test.py", line 90, in handle
    failures = test_runner.run_tests(test_labels)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/test/runner.py", line 532, in run_tests
    old_config = self.setup_databases()
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/test/runner.py", line 482, in setup_databases
    self.parallel, **kwargs
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/test/runner.py", line 726, in setup_databases
    serialize=connection.settings_dict.get("TEST", {}).get("SERIALIZE", True),
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/db/backends/base/creation.py", line 70, in create_test_db
    run_syncdb=True,
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/__init__.py", line 119, in call_command
    return command.execute(*args, **defaults)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/core/management/commands/migrate.py", line 87, in handle
    connection.prepare_database()
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/contrib/gis/db/backends/postgis/base.py", line 25, in prepare_database
    cursor.execute("CREATE EXTENSION IF NOT EXISTS postgis")
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/db/utils.py", line 95, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/home/ilse/myvenv/lib/python3.4/site-packages/django/db/backends/utils.py", line 62, in execute
    return self.cursor.execute(sql)
django.db.utils.InternalError: PostGIS is already installed in schema 'public', uninstall it first

```

In `django1.8` everything works as expected. 
Are there any changes in `django1.9` and `postgis` I am not aware of?