pkg.installed sources option doesn't work for .deb

Description

Using '- sources:' with a .rpm source works fine, but with a .deb, I get unpredictable results.

Setup

Nothing special, I put the .deb in a subdirectory with my SLS.

Steps to Reproduce the behavior

I was trying to install a fairly large .deb (the SentinelAgent client for the SentinelOne security package), but to exclude that I created a trivial .deb that just installs a README.

TrivialDeb:
  pkg.installed:
    - name: TrivialDeb
    - sources:
      - TrivialDeb: salt://Tricks/files/TrivialDeb.deb

Expected behavior

I can run exactly the same structure with an .rpm, and it installs fine every time.

Screenshots

This is what I end up with, occasionally, but it isn't deterministic. Sometimes I get partial success (it installs the file but 'fails', even though when I manually install the .deb with dpkg -i it doesn't generate an error.)

          ID: TrivialDeb_Package
    Function: pkg.installed
        Name: TrivialDeb
      Result: False
     Comment: An exception occurred in this state: Traceback (most recent call last):
                File "/usr/lib/python2.7/dist-packages/salt/state.py", line 1626, in call
                  **cdata['kwargs'])
                File "/usr/lib/python2.7/dist-packages/salt/loader.py", line 1492, in wrapper
                  return f(*args, **kwargs)
                File "/usr/lib/python2.7/dist-packages/salt/states/pkg.py", line 1103, in installed
                  **kwargs)
                File "/usr/lib/python2.7/dist-packages/salt/modules/aptpkg.py", line 562, in install
                  deb_info = __salt__['lowpkg.bin_pkg_info'](pkg_source)
                File "/usr/lib/python2.7/dist-packages/salt/modules/dpkg.py", line 64, in bin_pkg_info
                  if not os.path.exists(path):
                File "/usr/lib/python2.7/genericpath.py", line 26, in exists
                  os.stat(path)
              TypeError: coercing to Unicode: need string or buffer, bool found
     Started: 17:21:55.284741
    Duration: 1007.709 ms
     Changes:   

Versions Report

Salt Version:
           Salt: 3000.1
 
Dependency Versions:
           cffi: Not Installed
       cherrypy: 3.5.0
       dateutil: 2.4.2
      docker-py: Not Installed
          gitdb: 0.6.4
      gitpython: 1.0.1
         Jinja2: 2.8
        libgit2: Not Installed
       M2Crypto: 0.21.1
           Mako: 1.0.3
   msgpack-pure: Not Installed
 msgpack-python: 0.6.2
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.12 (default, Apr 15 2020, 17:07:12)
   python-gnupg: 0.3.8
         PyYAML: 3.11
          PyZMQ: 15.2.0
          smmap: 0.9.0
        timelib: Not Installed
        Tornado: 4.5.3
            ZMQ: 4.1.4
 
System Versions:
           dist: Ubuntu 16.04 xenial
         locale: UTF-8
        machine: x86_64
        release: 4.4.0-96-generic
         system: Linux
        version: Ubuntu 16.04 xenial

Additional context

I know I'm running an older Python, I promise to upgrade ASAP. I spent a lot of time trying various things other than upgrading my master, but I couldn't isolate or identify any problems. Turning up the debug didn't seem to help.

Reproduce the .deb case with the shown SLS, then trace the failure through salt/states/pkg.py, salt/modules/aptpkg.py, and salt/modules/dpkg.py. Compare the .deb and .rpm source paths; done means a local .deb installs reliably through pkg.installed without the reported TypeError or a false result.