##### SUMMARY
Ansible run fails and I want to retry the failed hosts with the --limit @windows.retry command and it fails with "ERROR! Unexpected Exception, this is probably a bug: string index out of range"

##### ISSUE TYPE
- Bug Report

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

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
$ ansible --version
ansible 2.9.0.dev0
  config file = /Users/tanner/projects/ansible.git/playbooks.git/celadonsystems.com/ansible.cfg
  configured module search path = [u'/Users/tanner/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/tanner/projects/ansible.git/ansible/lib/ansible
  executable location = /Users/tanner/projects/ansible.git/ansible/bin/ansible
  python version = 2.7.10 (default, Feb 22 2019, 21:55:15) [GCC 4.2.1 Compatible Apple LLVM 10.0.1 (clang-1001.0.37.14)]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
$ ansible-config dump --only-changed

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
Management host macOS 10.14.6
Managed hosts various releases of Windows

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

<!--- Paste example playbooks or commands between quotes below -->
Run ansible and have a failure so you get the retry file
```yaml
$ ansible-playbook -i testing ../windows.yml  --limit @../windows.retry
```

##### EXPECTED RESULTS
Ansible will run for just the failed hosts in the retry file

##### ACTUAL RESULTS
ERROR! Unexpected Exception, this is probably a bug: string index out of range

<!--- Paste verbatim command output between quotes -->
```paste below
ERROR! Unexpected Exception, this is probably a bug: string index out of range
```

self._loader = loader
        self._inventory = InventoryData()
        
        self._restriction = None
        self._subset = None
        
        self._hosts_patterns_cache = {}  
        self._pattern_cache = {}  
        
        if sources is None:
            self._sources = []
        elif isinstance(sources, string_types):
            self._sources = [sources]
        else:
            self._sources = sources
        
        self.parse_sources(cache=True)
    @property
    def localhost(self):
        return self._inventory.localhost
    @property
    def groups(self):