4220 beadm mount of old BE with zones fails "Read only filesystem"
4235 beadm(1M) mount options undocumented in man page

@@ -1267,10 +1267,14 @@
         case BE_ERR_ACCESS:
                 (void) fprintf(stderr, _("Unable to mount %s.\n"), obe_name);
                 (void) fprintf(stderr, _("You have insufficient privileges to "
                     "execute this command.\n"));
                 break;
+        case BE_ERR_NO_MOUNTED_ZONE:
+                (void) fprintf(stderr, _("Mounted on '%s'.\nUnable to mount "
+                    "one of %s's zone BE's.\n"), mountpoint, obe_name);
+                break;
         default:
                 (void) fprintf(stderr, _("Unable to mount %s.\n"), obe_name);
                 (void) fprintf(stderr, "%s\n", be_err_to_str(err));
         }