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##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
Add a --cacheonly option to the ansible yum module, similar to the --downloadonly option.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
lib/ansible/modules/packaging/os/yum.py

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
We have a group of Oracle servers that have no repository management server.  They update directly from Oracle's repositories.  Our thought is to do a "yum update --downloadonly" on all dev and prod servers.  Then we can update the dev servers first using "yum update --cacheonly" to test then updated and run the same command on the prod at a later time to make them consistent with the dev.
<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

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- Set best option to False, so that transactions are not limited to best candidates only.
    required: false
    type: bool
    default: "no"
    version_added: "2.11"
notes:
  - When used with a `loop:` each package will be processed individually, it is much more efficient to pass the list directly to the `name` option.
  - Group removal doesn't work if the group was installed with Ansible because
    upstream dnf's API doesn't properly mark groups as installed, therefore upon
    removal the module is unable to detect that the group is installed
    (https://bugzilla.redhat.com/show_bug.cgi?id=1620324)
requirements:
  - "python >= 2.6"
  - python-dnf
  - for the autoremove option you need dnf >= 2.0.1"
author:
  - Igor Gnatenko (@ignatenkobrain) <i.gnatenko.brain@gmail.com>
  - Cristian van Ee (@DJMuggs) <cristian at cvee.org>
  - Berend De Schouwer (@berenddeschouwer)
  - Adam Miller (@maxamillion) <admiller@redhat.com>
'''
EXAMPLES = '''
- name: Install the latest version of Apache
  dnf:
    name: httpd
    state: latest
- name: Install Apache >= 2.4
  dnf:
    name: httpd>=2.4
    state: present