fix error with delete host in inventory.py script (#4203)

* fix error with delete host in inventory.py script

* minor fix

contrib/inventory_builder/inventory.py

@@ -190,7 +190,7 @@ class KubesprayInventory(object):
             return [ip_address(ip).exploded for ip in range(start, end+1)]
 
         for host in hosts:
-            if '-' in host:
+            if '-' in host and not host.startswith('-'):
                 start, end = host.strip().split('-')
                 try:
                     reworked_hosts.extend(ips(start, end))