##### 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
if dns_name == '':
                for (iname, ivalue) in iteritems(interfaces):
                    if ivalue['management'] or not ivalue['static']:
                        this_dns_name = ivalue.get('dns_name', None)
                        if this_dns_name is not None and this_dns_name is not "":
                            dns_name = this_dns_name
            if dns_name == '' or dns_name is None:
                continue
            status = host['status']
            profile = host['profile']
            classes = host[orderby_keyname]
            if status not in self.inventory:
                self.inventory[status] = []
            self.inventory[status].append(dns_name)
            if profile not in self.inventory:
                self.inventory[profile] = []
            self.inventory[profile].append(dns_name)
            for cls in classes:
                if cls not in self.inventory:
                    self.inventory[cls] = []
                self.inventory[cls].append(dns_name)
            
            
            self.cache[dns_name] = host
            if "ks_meta" in host:
                for key, value in iteritems(host["ks_meta"]):
                    self.cache[dns_name][key] = value
        self.write_to_cache(self.cache, self.cache_path_cache)
        self.write_to_cache(self.inventory, self.cache_path_inventory)
    def get_host_info(self):