##### SUMMARY

```
master:/usr/local/lib/python2.7/site-packages/ansible/modules/system/sysctl.py", line 297, in reload_sysctl
UnboundLocalError: local variable 'err' referenced before assignment
```

- Bug exists in Ansible 2.7.11 and the latest git repo
- Related source file: https://github.com/ansible/ansible/blob/devel/lib/ansible/modules/system/sysctl.py#L278

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME

- sysctl

##### ANSIBLE VERSION
```paste below
$ ansible --version
ansible 2.7.11
  config file = /Users/zhb/projects/pro/ansible.cfg
  configured module search path = [u'/Users/zhb/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python2.7/site-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 2.7.16 (default, May 24 2019, 09:49:36) [GCC 4.2.1 Compatible Apple LLVM 10.0.1 (clang-1001.0.46.4)]
```

##### OS / ENVIRONMENT

- Host OS: macOS 10.14.5
- Target OS: OpenBSD 6.5 (amd64)
"""Expects two string values. It will split the string by whitespace
        and compare each value. It will return True if both lists are the same,
        contain the same elements and the same order."""
        if a is None or b is None:
            return False
        a = a.split()
        b = b.split()
        if len(a) != len(b):
            return False
        return len([i for i, j in zip(a, b) if i == j]) == len(a)
    def _parse_value(self, value):
        if value is None:
            return ''
        elif isinstance(value, bool):
            if value:
                return '1'
            else:
                return '0'
        elif isinstance(value, string_types):
            if value.lower() in BOOLEANS_TRUE:
                return '1'
            elif value.lower() in BOOLEANS_FALSE:
                return '0'
            else:
                return value.strip()
        else:
            return value
    def _stderr_failed(self, err):