[BUG] Salt exit with bound method Client.__del__ of <etcd.client.Client object at ignored

Description
After upgrading salt master and minion to 2019.2.4, we started getting an error
We have upgraded due to CVE issue

ERROR: Minions returned with non-zero exit code
Exception TypeError: TypeError("'NoneType' object is not callable",) in <bound method Client.__del__ of <etcd.client.Client object at 0x7f4f62781810>> ignored

This error occurs after several execution of salt run.
When we restart the salt-master then it goes for a while, but after few hours it starts appearing again

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

Steps to Reproduce the behavior
(Include debug logs if possible and relevant)

salt 'target' cmd.run 'ls -l /var' -l debug

[DEBUG   ] .Passing on saltutil error. Key 'u'retcode' missing from client return. This may be an error in the client
[DEBUG   ] return event: {'example1.com': {u'failed': True}}
[DEBUG   ] Could not LazyLoad etcd.init_kwargs: 'etcd.init_kwargs' is not available.
[INFO    ] etcd: Setting up client with params: {u'username': u'saltmaster', u'protocol': u'http', u'ca_cert': u'None', u'allow_redirect': False, u'srv_domain': None, u'host': u'192.168.1.98', u'read_timeout': 60, u'password': u'test_pass', u'port': 2379, u'allow_reconnect': True, u'cert': u'None'}
[DEBUG   ] Starting new HTTP connection (1): 192.168.1.98:2379
[DEBUG   ] http://192.168.1.98:2379 "GET /v2/machines HTTP/1.1" 200 23
[DEBUG   ] http://192.168.1.98:2379 "GET /v2/keys/salt_cache HTTP/1.1" 200 178
[DEBUG   ] http://192.168.1.98:2379 "GET /v2/keys/salt_cache/minions HTTP/1.1" 200 None
[DEBUG   ] http://192.168.1.98:2379 "GET /v2/keys/salt_cache/minions?recursive=true HTTP/1.1" 200 None
[DEBUG   ] Could not LazyLoad etcd.init_kwargs: 'etcd.init_kwargs' is not available.
[INFO    ] etcd: Setting up client with params: {u'username': u'saltmaster', u'protocol': u'http', u'ca_cert': u'None', u'allow_redirect': False, u'srv_domain': None, u'host': u'192.168.1.98', u'read_timeout': 60, u'password': u'test_pass', u'port': 2379, u'allow_reconnect': True, u'cert': u'None'}
[DEBUG   ] Starting new HTTP connection (1): 192.168.1.98:2379
[DEBUG   ] http://192.168.1.98:2379 "GET /v2/machines HTTP/1.1" 200 23
[DEBUG   ] http://192.168.1.98:2379 "GET /v2/keys/salt_cache HTTP/1.1" 200 178
[DEBUG   ] http://192.168.1.98:2379 "GET /v2/keys/salt_cache/minions?recursive=true HTTP/1.1" 200 None

[DEBUG   ] Closing IPCMessageSubscriber instance
ERROR: Minions returned with non-zero exit code
Exception TypeError: TypeError("'NoneType' object is not callable",) in <bound method Client.__del__ of <etcd.client.Client object at 0x7f4f62781810>> ignored

Warning on minion log:

2020-05-05 17:00:15,248 [salt.utils.parsers:1071][WARNING ][1844] Minion received a SIGTERM. Exiting.
2020-05-05 17:02:00,540 [salt.utils.parsers:1071][WARNING ][25113] Minion received a SIGTERM. Exiting.
2020-05-06 01:07:57,521 [salt.utils.parsers:1071][WARNING ][25358] Minion received a SIGTERM. Exiting.

For simple salt.run it occurs after 10-15 continuous salt call from master

Expected behavior
Error must go, instead it should print expected output

Screenshots
If applicable, add screenshots to help explain your problem.

Versions Report

salt --versions-report
Salt Version:
           Salt: 2019.2.4

Dependency Versions:
           cffi: 1.6.0
       cherrypy: Not Installed
       dateutil: 1.5
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.7.2
        libgit2: 0.26.4
        libnacl: Not Installed
       M2Crypto: 0.21.1
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.5.6
   mysql-python: Not Installed
      pycparser: 2.14
       pycrypto: 2.6.1
   pycryptodome: 3.9.7
         pygit2: 0.26.4
         Python: 2.7.5 (default, Jun 11 2019, 14:33:56)
   python-gnupg: 0.4.4
         PyYAML: 3.10
          PyZMQ: 15.3.0
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.2.1
            ZMQ: 4.1.4

System Versions:
           dist: redhat 7.6 Maipo
         locale: UTF-8
        machine: x86_64
        release: 3.10.0-1127.el7.x86_64
         system: Linux
        version: Red Hat Enterprise Linux Server 7.6

Additional context
Add any other context about the problem here.

Start by running the reported salt 'target' cmd.run 'ls -l /var' -l debug workflow against the stated Salt 2019.2.4 and etcd setup, then compare the master and minion logs with the versions report. Done means repeated calls no longer produce the Client.__del__ TypeError and return the expected command output without the related non-zero exit.