I am using the yum module to lock the release version for a RHEL 7.6 machine to 7.7 version. However the yum --releasever option does not set the release version to 7.7. I am using Ansible 2.7.10 version.
Here is the discussion regarding the issue: 
https://access.redhat.com/discussions/4774501

ISSUE TYPE
Bug Report

COMPONENT NAME
yum --releasever

ANSIBLE VERSION
2.7.10 

STEPS TO REPRODUCE
name: installing updated packages
yum:
name: '*'
state: latest
releasever: '7.7'

ACTUAL RESULTS
Play runs successfully however it does not update the release version of the server
behaviour.
  - 'Yum itself has two types of groups.  "Package groups" are specified in the
    rpm itself while "environment groups" are specified in a separate file
    (usually by the distribution).  Unfortunately, this division becomes
    apparent to ansible users because ansible needs to operate on the group
    of packages in a single transaction and yum requires groups to be specified
    in different ways when used in that way.  Package groups are specified as
    "@development-tools" and environment groups are "@^gnome-desktop-environment".
    Use the "yum group list hidden ids" command to see which category of group the group
    you want to install falls into.'
  - 'The yum module does not support clearing yum cache in an idempotent way, so it
    was decided not to implement it, the only method is to use command and call the yum
    command directly, namely "command: yum clean all"
    https://github.com/ansible/ansible/pull/31450#issuecomment-352889579'
# informational: requirements for nodes
requirements:
- yum
author:
    - Ansible Core Team
    - Seth Vidal (@skvidal)
    - Eduard Snesarev (@verm666)
    - Berend De Schouwer (@berenddeschouwer)
    - Abhijeet Kasurde (@Akasurde)
    - Adam Miller (@maxamillion)
'''
EXAMPLES = '''
- name: install the latest version of Apache
  yum:
    name: httpd
    state: latest