fix(update-alternatives): work around localvar_inherit

Author: akinomyoga

completions/update-alternatives

@@ -31,7 +31,7 @@ _comp_cmd_update_alternatives()
             ;;
     esac
 
-    local mode args i
+    local mode="" args i
 
     # find which mode to use and how many real args used so far
     for ((i = 1; i < cword; i++)); do