bug#23781: 25.0.95; read-string with HIST lexically bound

[Drew Adams]

> Well, the info node `(elisp) Variables' says:
> 
>    In Lisp, each variable is represented by a Lisp symbol (see
>    Symbols::).  The variable name is simply the symbol’s name [...]
> 
> and a symbol's name is a string (according to `symbol-name').  But maybe
> we should leave the bike shed before this gets too philosophical ;-)

That was written (and was true) back when Emacs had only dynamic
variables, that is, symbols that act as variables, with name
`symbol-name' and value `symbol-value'.

Unfortunately, the developer who added lexical binding to Emacs
Lisp was not very strong or motivated in the Doc department (by
his own admission), so that text was not amended.  At least that's
my guess for why it still says that.

Section `Variable Scoping' was added to the manual to present
lexical binding.  And there is some hint of it in node `Local
Variables'.  The rest of the doc seems to generally be talking
about dynamic variables (even if local, buffer-local, file-local,
etc.).