ash: make "locak VAR" unset VAR (bash does that)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash_test/ash-misc/local1.right b/shell/ash_test/ash-misc/local1.right
new file mode 100644
index 0000000..a2d121d
--- /dev/null
+++ b/shell/ash_test/ash-misc/local1.right
@@ -0,0 +1,4 @@
+A1:'A'
+A2:''
+A3:''
+A4:'A'