Bugs related to buffer-local tags-file-name

[Josiah Schwab]

Hello,

There is a collection of issues related to setting buffer-local values
of tags-file-name (either directly with setq-local or via
visit-tags-table).  Many of these have been around for a long time.

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=158
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=17326
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=23164

These bugs (and bugs merged into them) have clear steps to reproduce the
issues, as well as decent analysis (and in some cases proposed patches).

This morning, I reproduced a number of these with current release
version of (emacs 25.1) and the development version (git
c542fab20f53374dd0c71dce949ef370fc76fa48).

Could someone who understands etags.el take a look at these bugs?  It
seems possible that some minor refactoring might kill several of these
at once.

Josiah

P.S.  I posted to debbugs, but my simple set-up and some uniform
instructions are also available at

  https://github.com/jschwab/emacs-tags-issues