Fix the new -e handling. An empty cmd has to work for backwards compatibility.

st.c

@@ -4010,7 +4010,7 @@ main(int argc, char *argv[]) {
 		opt_class = EARGF(usage());
 		break;
 	case 'e':
-		if(argc > 1)
+		if(argc > 0)
 			--argc, ++argv;
 		goto run;
 	case 'f':