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##### SUMMARY
The `postgres_user` module does not commit changes if the variable groups is set. The create action will be commited, but any changes after that which do not change the `groups` variable will not be commited. This is due to [this line](https://github.com/ansible/ansible/blob/80bf24b17c52546c081b27e639499ba128824cf3/lib/ansible/modules/database/postgresql/postgresql_user.py#L855) which overrides the changed variable regardless of hte previous settings

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
`postgres_user`

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
prod@ansible # ansible --version
ansible 2.9.0
  config file = /root/ansible.cfg
  configured module search path = [u'/root/galaxy_roles/kafka_lib/library']
  ansible python module location = /root/env/local/lib/python2.7/site-packages/ansible
  executable location = /root/env/bin/ansible
  python version = 2.7.12 (default, Oct  8 2019, 14:14:10) [GCC 5.4.0 20160609]

```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
ANSIBLE_PIPELINING(/root/ansible.cfg) = True
ANSIBLE_SSH_RETRIES(/root/ansible.cfg) = 3
CACHE_PLUGIN(/root/ansible.cfg) = jsonfile
CACHE_PLUGIN_CONNECTION(/root/ansible.cfg) = /root/.ansible_jsonfile_cache
CACHE_PLUGIN_TIMEOUT(/root/ansible.cfg) = 86400000
DEFAULT_GATHERING(/root/ansible.cfg) = smart
DEFAULT_MODULE_PATH(env: ANSIBLE_LIBRARY) = [u'/root/galaxy_roles/kafka_lib/library']
HOST_KEY_CHECKING(env: ANSIBLE_HOST_KEY_CHECKING) = False
```

##### OS / ENVIRONMENT
Tested on mac and linux 


##### STEPS TO REPRODUCE
Run the following:

```yaml
- name: Create read group
  postgresql_user:
    name: read
    role_attr_flags: NOLOGIN
    state: present
  become: yes
  become_user: postgres

- name: Create/grant postgres user
  postgresql_user:
    name: some_user
    state: present
    groups: [read]
    password: abc123
  become: yes
  become_user: postgres
```

Then change something (such as password) without changing groups:
```yaml
- name: Create/grant postgres user
  postgresql_user:
    name: some_user
    state: present
    groups: [read]
    password: abc1234
  become: yes
  become_user: postgres
```
And run the playbook again. The play will be reported as `changed: false` and the password will not be updated.



##### EXPECTED RESULTS
Changes are commited without changing the groups var


##### ACTUAL RESULTS

Changes are only commited if the groups var is changed.
pass
#
def user_exists(cursor, user):
    
    if user == 'PUBLIC':
        return True
    query = "SELECT rolname FROM pg_roles WHERE rolname=%(user)s"
    cursor.execute(query, {'user': user})
    return cursor.rowcount > 0
def user_add(cursor, user, password, role_attr_flags, encrypted, expires, conn_limit):
    """Create a new database user (role)."""
    
    
    query_password_data = dict(password=password, expires=expires)
    query = ['CREATE USER "%(user)s"' %
             {"user": user}]
    if password is not None and password != '':
        query.append("WITH %(crypt)s" % {"crypt": encrypted})
        query.append("PASSWORD %(password)s")
    if expires is not None:
        query.append("VALID UNTIL %(expires)s")
    if conn_limit is not None:
        query.append("CONNECTION LIMIT %(conn_limit)s" % {"conn_limit": conn_limit})
    query.append(role_attr_flags)
    query = ' '.join(query)
    executed_queries.append(query)
    cursor.execute(query, query_password_data)
    return True
def user_should_we_change_password(current_role_attrs, user, password, encrypted):