avoid traceback on log owsexception (#95)

* avoid traceback exception dump as 'error' in case of raised OWSException indicating a valid unauthorized check

* update changelog

CHANGES.rst

@@ -4,6 +4,11 @@ Changes
 Unreleased
 ==========
 
+Changes:
+
+* Reduce log level of ``"failed security check"`` from ``exception`` to ``warning`` as it corresponds to the expected
+  code behavior (unauthorised access) when ``OWSException`` is raised, instead of dumping an unhandled error traceback.
+
 0.5.2 (2019-07-11)
 ==================
 

twitcher/tweens.py

@@ -27,7 +27,7 @@ def ows_security_tween(request):
             security.check_request(request)
             return handler(request)
         except OWSException as err:
-            LOGGER.exception("security check failed.")
+            LOGGER.warning("security check failed.")
             return err
         except Exception as err:
             LOGGER.exception("unknown error")