Salt: [BUG] Salt override previously defined filterwarnings

[jynolen]

Description
The default behavior of filterwarnings is to push new rules to the top of the filter list.
If filter are inplace before salt init (like pytest) it will override configuration

* Test on *
https://github.com/saltstack/salt/tree/v3000.2

Setup
test.py

import salt.module.config
import pytest

@pytest.mark.filterwarnings("ignore:DeprecationWarning")
def test_dummy():
    pass

pytest.ini

[pytest]
filterwarnings = ignore::DeprecationWarning:^salt:%

Steps to Reproduce the behavior

$ pytest test.py

=========================================================================================== test session starts ===========================================================================================
platform linux -- Python 3.7.3, pytest-5.4.3, py-1.8.1, pluggy-0.13.1
rootdir: /opt/salt_test, inifile: pytest.ini
plugins: requests-mock-1.8.0
collected 1 item

test.py .                                                                                                                                                                     [100%]

============================================================================================ warnings summary =============================================================================================
vendor/salt/salt/ext/tornado/httputil.py:107
  /opt/work/salt_custom/vendor/salt/salt/ext/tornado/httputil.py:107: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
    class HTTPHeaders(collections.MutableMapping):

-- Docs: https://docs.pytest.org/en/latest/warnings.html
====================================================================================== 1 passed, 1 warning in 0.30s =======================================================================================

Expected behavior

$ pytest test.py
=========================================================================================== test session starts ===========================================================================================
platform linux -- Python 3.7.3, pytest-5.4.3, py-1.8.1, pluggy-0.13.1
rootdir: /opt/salt_test, inifile: pytest.ini
plugins: requests-mock-1.8.0
collected 1 item

test.py .                                                                                                                                                                     [100%]

============================================================================================ 1 passed in 0.32s ============================================================================================

Fix`
Patch file content

--- salt/salt/__init__.py        2020-06-08 11:30:02.450452983 +0200
+++ patch.py  2020-06-08 11:33:09.276345191 +0200
@@ -33,21 +33,23 @@
     '',  # No deprecation message match
     DeprecationWarning,  # This filter is for DeprecationWarnings
-    r'^(salt|salt\.(.*))$'  # Match module(s) 'salt' and 'salt.<whatever>'
+    r'^(salt|salt\.(.*))$',  # Match module(s) 'salt' and 'salt.<whatever>'
+    append=True
 )

 # While we are supporting Python2.6, hide nested with-statements warnings
 warnings.filterwarnings(
     'ignore',
     'With-statements now directly support multiple context managers',
-    DeprecationWarning
+    DeprecationWarning,
+    append=True
 )

 # Filter the backports package UserWarning about being re-imported
 warnings.filterwarnings(
     'ignore',
     '^Module backports was already imported from (.*), but (.*) is being added to sys.path$',
-    UserWarning
+    UserWarning,
+    append=True
 )

[frogunder]

@jynolen Thank you for reporting this issue.

Seems like you have a fix for it. Do you wanna submit an PR to address this issue?

Thanks.

[jynolen]

@frogunder Please find PR #57598 for the fix

[jynolen]

ANy updates about this ?