job cache success often incorrectly false

Description of Issue/Question

I often see successful state.apply jobs that aren't flagged as a success by the pgjsonb job cache.

Setup

master_job_cache: pgjsonb

Steps to Reproduce Issue

I've noticed if I run salt-call state.apply on a minion and it completes successfully, it is often (always?) not flagged as a success by pgjsonb. If, however, I run salt-call --return=local state.apply it is flagged as a success both in pgjsonb and in local.

Jobs run from the master seem to set the success more accurately.

Versions Report

Salt Version:
           Salt: 2017.7.2

Dependency Versions:
           cffi: Not Installed
       cherrypy: Not Installed
       dateutil: 2.4.2
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.8
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: Not Installed
           Mako: 1.0.3
   msgpack-pure: Not Installed
 msgpack-python: 0.4.6
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.12 (default, Dec  4 2017, 14:50:18)
   python-gnupg: Not Installed
         PyYAML: 3.11
          PyZMQ: 15.2.0
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.2.1
            ZMQ: 4.1.4

System Versions:
           dist: Ubuntu 16.04 xenial
         locale: UTF-8
        machine: x86_64
        release: 4.4.0-1047-aws
         system: Linux
        version: Ubuntu 16.04 xenial

Start by tracing the pgjsonb job-cache handling for locally invoked salt-call state.apply jobs, comparing it with --return=local and master-triggered jobs. Reproduce the reported success discrepancy using the issue's Salt 2017.7.2 setup, then verify that successful jobs are consistently recorded with success in pgjsonb.