##### SUMMARY

SyntaxWarning over using is for comparison of literals. The fix is simple and is a good beginner issue.

```
contrib/inventory/cobbler.py:218: SyntaxWarning: "is not" with a literal. Did you mean "!="?
  if this_dns_name is not None and this_dns_name is not "":
```

##### ISSUE TYPE

- Bug Report

##### COMPONENT NAME

cobbler

##### ANSIBLE VERSION

devel branch
""" Get variables about a specific host """
        if not self.cache or len(self.cache) == 0:
            
            self.load_cache_from_cache()
        if self.args.host not in self.cache:
            
            self.update_cache()
            if self.args.host not in self.cache:
                
                return self.json_format_dict({}, True)
        return self.json_format_dict(self.cache[self.args.host], True)
    def push(self, my_dict, key, element):
        """ Pushed an element onto an array that may not have been defined in the dict """
        if key in my_dict:
            my_dict[key].append(element)
        else:
            my_dict[key] = [element]
    def load_inventory_from_cache(self):