sleep: fix error exit when called as "sh" builtin

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

coreutils/sleep.c

@@ -74,7 +74,8 @@ int sleep_main(int argc UNUSED_PARAM, char **argv)
 	++argv;
 	if (!*argv) {
 		/* Without this, bare "sleep" in ash shows _ash_ --help */
-		if (ENABLE_ASH_SLEEP && applet_name[0] != 's') {
+		/* (ash can be the "sh" applet as well, so check 2nd char) */
+		if (ENABLE_ASH_SLEEP && applet_name[1] != 'l') {
 			bb_simple_error_msg("sleep: missing operand");
 			return EXIT_FAILURE;
 		}