Ensure users with undefined ACL are treated as readable (#4795)

* Adds test to reproduce issue #4790

* Attempt to allow failure on node STABLE

* Use new format for apt packages

.travis.yml

@@ -7,8 +7,9 @@ services:
   - docker
 addons:
   postgresql: '9.5'
-  apt_packages:
-  - postgresql-9.5-postgis-2.3
+  apt:
+    packages:
+      - postgresql-9.5-postgis-2.3
 branches:
   only:
   - master
@@ -32,6 +33,9 @@ env:
   - PARSE_SERVER_TEST_DB=postgres
   - PARSE_SERVER_TEST_CACHE=redis
   - NODE_VERSION=stable
+matrix:
+  allow_failures:
+    - env: NODE_VERSION=stable
 before_install:
 - nvm install $NODE_VERSION
 - nvm use $NODE_VERSION