Fix postgres test by adhering to flask specs to return none in case userid not valid

.travis.yml

@@ -18,42 +18,42 @@ env:
   matrix:
     - TOX_ENV=py27-cdh-airflow_backend_mysql
     - TOX_ENV=py27-cdh-airflow_backend_sqlite
-#    - TOX_ENV=py27-cdh-airflow_backend_postgres
+    - TOX_ENV=py27-cdh-airflow_backend_postgres
     - TOX_ENV=py27-hdp-airflow_backend_mysql
     - TOX_ENV=py27-hdp-airflow_backend_sqlite
-#    - TOX_ENV=py27-hdp-airflow_backend_postgres
+    - TOX_ENV=py27-hdp-airflow_backend_postgres
     - TOX_ENV=py34-cdh-airflow_backend_mysql
     - TOX_ENV=py34-cdh-airflow_backend_sqlite
-#    - TOX_ENV=py34-cdh-airflow_backend_postgres
+    - TOX_ENV=py34-cdh-airflow_backend_postgres
     - TOX_ENV=py34-hdp-airflow_backend_mysql
     - TOX_ENV=py34-hdp-airflow_backend_sqlite
-#    - TOX_ENV=py34-hdp-airflow_backend_postgres
+    - TOX_ENV=py34-hdp-airflow_backend_postgres
 matrix:
   exclude:
     - python: "3.4"
       env: TOX_ENV=py27-cdh-airflow_backend_mysql
     - python: "3.4"
       env: TOX_ENV=py27-cdh-airflow_backend_sqlite
-#    - python: "3.4"
-#      env: TOX_ENV=py27-cdh-airflow_backend_postgres
+    - python: "3.4"
+      env: TOX_ENV=py27-cdh-airflow_backend_postgres
     - python: "3.4"
       env: TOX_ENV=py27-hdp-airflow_backend_mysql
     - python: "3.4"
       env: TOX_ENV=py27-hdp-airflow_backend_sqlite
-#    - python: "3.4"
-#      env: TOX_ENV=py27-hdp-airflow_backend_postgres
+    - python: "3.4"
+      env: TOX_ENV=py27-hdp-airflow_backend_postgres
     - python: "2.7"
       env: TOX_ENV=py34-cdh-airflow_backend_mysql
     - python: "2.7"
       env: TOX_ENV=py34-cdh-airflow_backend_sqlite
-#    - python: "2.7"
-#      env: TOX_ENV=py34-cdh-airflow_backend_postgres
+    - python: "2.7"
+      env: TOX_ENV=py34-cdh-airflow_backend_postgres
     - python: "2.7"
       env: TOX_ENV=py34-hdp-airflow_backend_mysql
     - python: "2.7"
       env: TOX_ENV=py34-hdp-airflow_backend_sqlite
-#    - python: "2.7"
-#      env: TOX_ENV=py34-hdp-airflow_backend_postgres
+    - python: "2.7"
+      env: TOX_ENV=py34-hdp-airflow_backend_postgres
 cache:
   directories:
     - $HOME/.wheelhouse/

airflow/contrib/auth/backends/kerberos_auth.py

@@ -72,6 +72,9 @@ class KerberosUser(models.User):
 
 @login_manager.user_loader
 def load_user(userid):
+    if not userid:
+        return None
+
     session = settings.Session()
     user = session.query(models.User).filter(models.User.id == userid).first()
     session.expunge_all()

airflow/contrib/auth/backends/ldap_auth.py

@@ -97,6 +97,9 @@ class LdapUser(models.User):
 
 @login_manager.user_loader
 def load_user(userid):
+    if not userid:
+        return None
+    
     session = settings.Session()
     user = session.query(models.User).filter(models.User.id == userid).first()
     session.expunge_all()