[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 f1e8be7e..f0ccad86 100644
--- a/sanic/app.py
+++ b/sanic/app.py
@@ -33,9 +33,7 @@ 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 and
-                log_config):
+        if not logging.root.handlers and log.level == logging.NOTSET:
             formatter = logging.Formatter(
                 "%(asctime)s: %(levelname)s: %(message)s")
             handler = logging.StreamHandler()
diff --git a/tests/test_logging.py b/tests/test_logging.py
index fc26ca93..d6911d86 100644
--- a/tests/test_logging.py
+++ b/tests/test_logging.py
@@ -1,5 +1,7 @@
-import asyncio
 import uuid
+from importlib import reload
+
+from sanic.config import LOGGING
 from sanic.response import text
 from sanic import Sanic
 from io import StringIO
@@ -10,6 +12,11 @@ function: %(funcName)s(); \\
 message: %(message)s'''
 
 
+def reset_logging():
+    logging.shutdown()
+    reload(logging)
+
+
 def test_log():
     log_stream = StringIO()
     for handler in logging.root.handlers[:]:
@@ -32,5 +39,19 @@ def test_log():
     log_text = log_stream.getvalue()
     assert rand_string in log_text
 
+
+def test_default_log_fmt():
+
+    reset_logging()
+    Sanic()
+    for fmt in [h.formatter for h in logging.getLogger('sanic').handlers]:
+        assert fmt._fmt == LOGGING['formatters']['simple']['format']
+
+    reset_logging()
+    Sanic(log_config=None)
+    for fmt in [h.formatter for h in logging.getLogger('sanic').handlers]:
+        assert fmt._fmt == "%(asctime)s: %(levelname)s: %(message)s"
+
+
 if __name__ == "__main__":
     test_log()
['sanic/app.py', 'tests/test_logging.py']