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##### SUMMARY
<!--- Explain the problem briefly below, add suggestions to wording or structure -->
The [PSRP documentation](https://docs.ansible.com/ansible/latest/plugins/connection/psrp.html) mentions `ansible_psrp_connection_backoff` but this seems to be incorrect. The code appears to refer to `ansible_psrp_reconnection_backoff` instead (`reconnection` vs `connection`).
<!--- HINT: Did you know the documentation has an "Edit on GitHub" link on every page ? -->

##### ISSUE TYPE
- Documentation Report

##### COMPONENT NAME
<!--- Write the short name of the rst file, module, plugin, task or feature below, use your best guess if unsure -->
PSRP
lib/ansible/plugins/connection/psrp.py

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.8.0.dev0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python2.7/dist-packages/ansible-2.8.0.dev0-py2.7.egg/ansible
  executable location = /usr/local/bin/ansible
  python version = 2.7.15rc1 (default, Nov 12 2018, 14:31:15) [GCC 7.3.0]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
None
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. OS version, browser, etc. -->
Linux, Ubuntu 18.04.2 LTS

##### ADDITIONAL INFORMATION
<!--- Describe how this improves the documentation, e.g. before/after situation or screenshots -->
None.
<!--- HINT: You can paste gist.github.com links for larger files -->
"psrp connection failure during runspace open: %s"
                    % to_native(e)
                )
            except (ConnectionError, ConnectTimeout) as e:
                raise AnsibleConnectionFailure(
                    "Failed to connect to the host via PSRP: %s"
                    % to_native(e)
                )
            self._connected = True
        return self
    def reset(self):
        display.vvvvv("PSRP: Reset Connection", host=self._psrp_host)
        self.runspace = None
        self._connect()
    def exec_command(self, cmd, in_data=None, sudoable=True):
        super(Connection, self).exec_command(cmd, in_data=in_data,
                                             sudoable=sudoable)
        if cmd.startswith(" ".join(_common_args) + " -EncodedCommand"):
            
            
            
            b_command = base64.b64decode(cmd.split(" ")[-1])
            script = to_text(b_command, 'utf-16-le')
            in_data = to_text(in_data, errors="surrogate_or_strict", nonstring="passthru")
            if in_data and in_data.startswith(u"#!"):
                
                
                
                
                interpreter = to_native(in_data.splitlines()[0][2:])