Redis server not launched - hangs waiting for connection

Nobody has claimed this yet.

Steps to reproduce:

```
virtualenv -p python3.6 test_dummy_env
source test_dummy_env/bin/activate
pip install pytest-server-fixtures redis
```

```python
# testit.py
def test_it(redis_server):
redis_server.api.set('key', 1)
assert redis_server.api.get('key') == 1
```

```
$ pytest testit.py --fulltrace -s
======================================================================================================================== test session starts =========================================================================================================================
platform linux -- Python 3.6.1, pytest-3.1.3, py-1.4.34, pluggy-0.4.0
rootdir: /home/rob/code/observer, inifile: pytest.ini
plugins: shutil-1.2.11, server-fixtures-1.2.11
collected 1 item s

testit.py pinging Redis at 127.75.17.85:20407 db 0
server not up yet (Error 111 connecting to 127.75.17.85:20407. Connection refused.)
pinging Redis at 127.75.17.85:20407 db 0
server not up yet (Error 111 connecting to 127.75.17.85:20407. Connection refused.)
pinging Redis at 127.75.17.85:20407 db 0
server not up yet (Error 111 connecting to 127.75.17.85:20407. Connection refused.)
pinging Redis at 127.75.17.85:20407 db 0
server not up yet (Error 111 connecting to 127.75.17.85:20407. Connection refused.)
pinging Redis at 127.75.17.85:20407 db 0
server not up yet (Error 111 connecting to 127.75.17.85:20407. Connection refused.)
pinging Redis at 127.75.17.85:20407 db 0
server not up yet (Error 111 connecting to 127.75.17.85:20407. Connection refused.)
pinging Redis at 127.75.17.85:20407 db 0
server not up yet (Error 111 connecting to 127.75.17.85:20407. Connection refused.)
```

`redis-server --version`
> Redis server v=3.0.6 sha=00000000:0 malloc=jemalloc-3.6.0 bits=64 build=687a2a319020fa42

`lsb_release -a`
```
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.2 LTS
Release: 16.04
Codename: xenial
```
-----

While pytest is running, if I check the process list, there's no `redis-server` process present.

Start by reproducing the issue with testit.py, pytest, and the redis_server fixture described in the report, then inspect the fixture's server-launch path. Done means the fixture starts a redis-server process and the shown test completes successfully instead of waiting indefinitely for a connection.

Written by the indexing model from the issue text.