Throw an error if general/mailman/password is not set.

collab/mailman/addmmlist.in

 #!/usr/bin/perl -wT
 #
 # EMULAB-COPYRIGHT
-# Copyright (c) 2005 University of Utah and the Flux Group.
+# Copyright (c) 2005, 2006 University of Utah and the Flux Group.
 # All rights reserved.
 #
 use English;
@@ -168,6 +168,9 @@ if ($listtype eq "admin") {
     if (! TBGetSiteVar("general/mailman/password", \$listpasswd)) {
 	fatal("Could not get mailman admin password from sitevars!");
     }
+    if (!defined($listpasswd) || $listpasswd eq "") {
+	fatal("mailman admin password sitevar is not set!");
+    }
 }
 else {
     # A user created list.