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##### SUMMARY
Ansible in dnf.py uses a private attributes (in this case it is an internal cache for security filters - base._update_security_filters). Using private attributes could result in random fails, because they could be even removed without announcement because it is not API.


        filters = []
        if self.bugfix:
            key = {'advisory_type__eq': 'bugfix'}
            filters.append(base.sack.query().upgrades().filter(**key))
        if self.security:
            key = {'advisory_type__eq': 'security'}
            filters.append(base.sack.query().upgrades().filter(**key))
        if filters:
            base._update_security_filters = filters

Also I an not sure if it works like expected (there is a difference in dnf upgrade, and dnf upgrade-minimal) and I don't know what was expected from ansible.

I also propose a new API in dnf that could resolve the issue (https://github.com/rpm-software-management/dnf/pull/1715). Any comment or suggestion is welcome
 
##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
dnf

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
devel
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->


##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

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##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->


##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below

```

#
from __future__ import absolute_import, division, print_function
__metaclass__ = type
DOCUMENTATION = '''
---
module: dnf
version_added: 1.9
short_description: Manages packages with the I(dnf) package manager
description:
     - Installs, upgrade, removes, and lists packages and groups with the I(dnf) package manager.
options:
  name:
    description:
      - "A package name or package specifier with version, like C(name-1.0).
        When using state=latest, this can be '*' which means run: dnf -y update.
        You can also pass a url or a local path to a rpm file.
        To operate on several packages this can accept a comma separated string of packages or a list of packages."
      - Comparison operators for package version are valid here C(>), C(<), C(>=), C(<=). Example - C(name>=1.0)
      - You can also pass an absolute path for a binary which is provided by the package to install.
        See examples for more information.
    required: true