bug#27772: 25.2; Choosing tags files

[Eli Zaretskii]

> From: npostavs@users.sourceforge.net
> Date: Sun, 06 Aug 2017 21:45:56 -0400
> Cc: 27772@debbugs.gnu.org
> 
> The problem is that the buffer gets changed by the time we reach there.
> The following patch seems to fix it (no need to explicitly use
> `buffer-local-variables' since normal variable access will check the
> buffer-local value first.

Seems reasonable, thanks.

> * lisp/progmodes/etags.el (visit-tags-table-buffer): Save the current
                                                                ^^^^^^^
You meant "current buffer", I presume.

Do etags-tests.el still pass after this change?  If so, would it be
possible to add a test for this bug?

Other than that, LGTM.