fix the get_hosts() error in get_groups returning a dict not a list of group objects

lib/ansible/inventory.py

@@ -73,7 +73,7 @@ class Inventory(object):
         hosts = {}
         patterns = pattern.replace(";",":").split(":")
 
-        for group in self.get_groups():
+        for (groupname, group) in self.get_groups().items():
             for host in group.get_hosts():
                 for pat in patterns:
                     if group.name == pat or pat == 'all' or self._match(host.name, pat):