ash: fix typo

diff --git a/shell/ash.c b/shell/ash.c
index 5348e95..1eb29eb 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -7961,7 +7961,7 @@
 #if NOR + 1 != NSEMI
 #error NOR + 1 != NSEMI
 #endif
-		unsigned is_or = is_or = n->type - NAND;
+		unsigned is_or = n->type - NAND;
 		evaltree(
 			n->nbinary.ch1,
 			(flags | ((is_or >> 1) - 1)) & EV_TESTED