Pin pylint version & fix linting error

Author: jonathanlloyd

.travis.yml

@@ -5,7 +5,6 @@ python:
 install:
   - pip install -Ur requirements.txt
   - pip install -Ur dev_requirements.txt
-  - pip install codecov
 script:
   - python -m pylint ./pusher_push_notifications/*.py
   - python -m nose -s --with-coverage

dev_requirements.txt

@@ -1,4 +1,5 @@
 nose==1.3.7
-pylint
+pylint==1.9.4
 requests-mock==1.5.2
 collective.checkdocs==0.2
+codecov==2.0.15

pusher_push_notifications/__init__.py

@@ -57,11 +57,11 @@ def _handle_http_error(response_body, status_code):
     )
     if status_code == 401:
         raise PusherAuthError(error_string)
-    elif status_code == 404:
+    if status_code == 404:
         raise PusherMissingInstanceError(error_string)
-    elif 400 <= status_code < 500:
+    if 400 <= status_code < 500:
         raise PusherValidationError(error_string)
-    elif 500 <= status_code < 600:
+    if 500 <= status_code < 600:
         raise PusherServerError(error_string)