bug#12938: 24.2; Lexical binding leaks into package-install somehow

[Glenn Morris]

I guess this could be summarized as:

mkdir foo
echo '(eval-when-compile (message "lex = %s" lexical-binding))' > foo/bar.el

Create test.el with contents

  ;; -*- lexical-binding: t -*-
  (byte-recompile-directory "foo/" 0)

emacs -Q --batch -l ./test.el
  -> lex = t