<!--- Verify first that your issue is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Explain the problem briefly below -->

##### ISSUE TYPE
- Bug Report

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

postgresql_slot, postgresql_user

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.8.3
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['~/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.7.4 (default, Jul 16 2019, 07:12:58) [GCC 9.1.0]
```

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

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

<!--- Paste example playbooks or commands between quotes below -->
```yaml
- postgresql_user:
    name: user1
    password: password
  become: true
  become_user: postgres

- postgresql_slot:
    name: slot1
  become: true
  become_user: postgres
```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
Consistent warnings. Either both postgresql_user and postgresql_slot should give a warning or neither should.

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->
postgresql_slot gives warning "[WARNING]: Database name has not been passed, used default database to connect to." but postgresql_user doesn't, even though both of them have not specified a database.
"""Reset tablespace setting.
        Return True if success, otherwise, return False.
        args:
            setting (str) -- string in format "setting_name = 'setting_value'"
        """
        query = "ALTER TABLESPACE %s RESET (%s)" % (pg_quote_identifier(self.name, 'database'), setting)
        return exec_sql(self, query, ddl=True)
    def __set_setting(self, setting):
        """Set tablespace setting.
        Return True if success, otherwise, return False.
        args:
            setting (str) -- string in format "setting_name = 'setting_value'"
        """
        query = "ALTER TABLESPACE %s SET (%s)" % (pg_quote_identifier(self.name, 'database'), setting)
        return exec_sql(self, query, ddl=True)
#
def main():