_reply_compgen_array: Fix leaking to environment

contrib/mount

@@ -17,7 +17,7 @@ _reply_compgen_array()
     # One round of escape is because we want to reply with escaped arguments. A
     # second round is required because compgen -W will helpfully expand it's
     # argument.
-    local wlist
+    local i wlist
     for i in ${!COMPREPLY[*]}; do
         local q=`printf %q "${COMPREPLY[$i]}"`
         wlist+=$(quote "$q")$'\n'