Unicode decoding error in user.present state when /etc/login.defs is read

Description of Issue

I'm getting a unicode decode error every time the user.present state runs on Ubuntu 16.04 with Python 3 and salt 2019.2.2. The error is happening in the code that reads the /etc/login.defs file.

2019-12-19 01:04:32,499 [salt.state       :322 ][ERROR   ][19335] An exception occurred in this state: Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/salt/state.py", line 1933, in call
    **cdata['kwargs'])
  File "/usr/lib/python3/dist-packages/salt/loader.py", line 1951, in wrapper
    return f(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/salt/states/user.py", line 756, in present
    if __salt__['user.add'](**params):
  File "/usr/lib/python3/dist-packages/salt/modules/useradd.py", line 155, in add
    for line in fp_:
  File "/usr/lib/python3.5/encodings/ascii.py", line 26, in decode
    return codecs.ascii_decode(input, self.errors)[0]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 6962: ordinal not in range(128)

I'm not having this problem on Ubuntu 18.04.

Setup

(Please provide relevant configs and/or SLS files (Be sure to remove sensitive info).)

Steps to Reproduce Issue

(Include debug logs if possible and relevant.)

Versions Report

# salt-minion --versions-report
Salt Version:
           Salt: 2019.2.2

Dependency Versions:
           cffi: 1.13.2
       cherrypy: Not Installed
       dateutil: 2.8.0
      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: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.4.6
   mysql-python: Not Installed
      pycparser: 2.19
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 3.5.2 (default, Oct  8 2019, 13:06:37)
   python-gnupg: 0.3.8
         PyYAML: 5.1.2
          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: 4.4.0-1087-aws
         system: Linux
        version: Ubuntu 16.04 xenial

Start in salt/modules/useradd.py around line 155, where /etc/login.defs is read during user.add, and trace the user.present path in salt/states/user.py. Reproduce the Ubuntu 16.04 Python 3 failure with non-ASCII content in login.defs; done means user.present no longer raises the reported UnicodeDecodeError.