ash: fix unset in standalone mode

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash.c b/shell/ash.c
index fcaa7b1..74fe861 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -7252,6 +7252,7 @@
 #if ENABLE_FEATURE_SH_STANDALONE
 	if (applet_no >= 0) {
 		if (APPLET_IS_NOEXEC(applet_no)) {
+			clearenv();
 			while (*envp)
 				putenv(*envp++);
 			run_applet_no_and_exit(applet_no, argv);