Make --role-holder return sane result

src/hostinfo.py

@@ -354,7 +354,7 @@ if __name__ == '__main__':
     if options.role_holder:
         who = hostinfo.role.holder(tree, options.role_holder)
         print who
-        pass
+        sys.exit(0)
         
     if options.yp:
         for (f, c) in hostinfo.yp.generate(tree, options.yp_auto_domain):