add an option to set server realm for all clients

vm/kojivmd

@@ -128,6 +128,7 @@ def get_options():
                 'krbservice': 'host',
                 'krb_rdns': True,
                 'krb_canon_host': False,
+                'krb_server_realm': None,
                 'server': None,
                 'user': None,
                 'password': None,

vm/kojivmd.conf

@@ -45,6 +45,9 @@ from_addr=Koji Build System <buildsys@example.com>
 ;the service name of the principal being used by the hub
 ;krbservice = host
 
+;The realm of server principal. Using client's realm if not set
+;krb_server_realm = EXAMPLE.COM
+
 ;configuration for SSL authentication
 
 ;client certificate