[Errno 13] Permission denied: '/access.log' with disabled debug & logging?
With:

```text
app.run(host=API_HOST, port=PORT, sock=None, debug=False, workers=API_WORKERS, log_config=None)
```

```text
app = Sanic(__name__)
  File "/usr/local/anaconda/envs/proj/lib/python3.6/site-packages/sanic/app.py", line 33, in __init__
    logging.config.dictConfig(log_config)
  File "/usr/local/anaconda/envs/proj/lib/python3.6/logging/config.py", line 795, in dictConfig
    dictConfigClass(config).configure()
  File "/usr/local/anaconda/envs/proj/lib/python3.6/logging/config.py", line 566, in configure
    '%r: %s' % (name, e))
ValueError: Unable to configure handler 'accessTimedRotatingFile': [Errno 13] Permission denied: '/access.log'
```
diff --git a/sanic/app.py b/sanic/app.py
index f6b1e84e..01af3526 100644
--- a/sanic/app.py
+++ b/sanic/app.py
@@ -33,7 +33,9 @@ class Sanic:
             logging.config.dictConfig(log_config)
         # Only set up a default log handler if the
         # end-user application didn't set anything up.
-        if not logging.root.handlers and log.level == logging.NOTSET:
+        if not (logging.root.handlers and
+                log.level == logging.NOTSET and
+                log_config):
             formatter = logging.Formatter(
                 "%(asctime)s: %(levelname)s: %(message)s")
             handler = logging.StreamHandler()
['sanic/app.py']