Error passing Pillar data to slack engine

Description of Issue

Unable to pass Pillar data to !state.apply command.
For eg. ! state.apply pillar=‘{“editPackage”: “vim”}’ target=*
It throws error in salt master log.
It is similar like #39783

Setup

/etc/salt/master:

file_roots:
  base:
    - /opt/salt/base
pillar_roots:
  base:
    - /opt/pillar/base
log_file: /var/log/salt/master
log_level: debug
engines_dirs:
  - /opt/engines

engines:
  - slack:
      token: 'TOKEN VALUE'
      control: True
      fire_all: false
      groups_pillar_name: 'slack_engine:groups_pillar'
      groups:
        default:
          users:
            - '*'
          commands:
            - test.ping
            - state.apply 
            - grains.ls
            - cmd.run
            - list_jobs
            - list_commands
          aliases:
            list_jobs:
              cmd: jobs.list_jobs
            list_commands:
              cmd: 'pillar.get salt:engines:slack:valid_commands target=* tgt_type=glob'
            ping_all:
              cmd: test.ping target='*'
          default_target:
            target: <MASTER MINION ID>
            tgt_type: list

/opt/salt/base/top.sls:

base:
  '*':
    - package

/opt/salt/base/package.sls:

editpackage:
  pkg.installed:
    - name: {{ pillar['editPackage']  }}

Steps to Reproduce Issue

Command executed in slackbot:

! state.apply pillar=‘{“editPackage”: “vim”}’ target=*

It shows cmdline in master log:

u'cmdline': [u'state.apply', u'pillar=\u2018{\u201ceditPackage\u201d:', u'\u201cvim\u201d}\u2019']

and throw below errors in /var/log/salt/master:

[CRITICAL][30693] Engine 'slack' could not be started!
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/salt/engines/__init__.py", line 132, in run
    self.engine[self.fun](**kwargs)
  File "/opt/engines/slack.py", line 849, in start
    raise Exception('{}'.format(traceback.format_exc()))
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 671: ordinal not in range(128)

Versions Report

[root@ip-172-31-13-97 ~]# salt --versions-report
Salt Version:
           Salt: 2019.2.2
 
Dependency Versions:
           cffi: 1.6.0
       cherrypy: unknown
       dateutil: 2.6.0
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.7.2
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: 0.31.0
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.5.6
   mysql-python: Not Installed
      pycparser: 2.14
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.16 (default, Sep 13 2019, 20:28:21)
   python-gnupg: Not Installed
         PyYAML: 3.11
          PyZMQ: 15.3.0
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.2.1
            ZMQ: 4.1.4
 
System Versions:
           dist:   
         locale: UTF-8
        machine: x86_64
        release: 4.14.152-127.182.amzn2.x86_64
         system: Linux
        version: Not Installed

Start with salt/engines/init.py around line 132 and the Slack engine's start function around /opt/engines/slack.py line 849. Reproduce the command with the quoted pillar data and inspect how the cmdline is parsed and decoded. Done means the pillar argument reaches state.apply without the UnicodeDecodeError and the engine remains running.