Hi Bastien,


    >> Loading tags from a #+SETUPFILE is causing inconsistent behavior
    >> in the tag-selection for both in-buffer selection via C-c C-q
    >> (`org-set-tags-command`) and in-agenda selection via :
    >> (`org-agenda-set-tags`).

    Bastien> Thanks a lot for reporting this and for the test case, it
    Bastien> should be fixed now.

    Bastien> All: the fix involves checking for a #+setupfile directive
    Bastien> when processing Org buffers for building the agenda.  This
    Bastien> may lead to some slow down when your agenda is built from
    Bastien> many files.  Let me know if you notice some weirdness.

Thanks a lot for the fix.  The test files are now behaving properly
after the fix (I am on orgmode git development head at commit
36848fdec9eb8c9c17a2e98cd742af1f9f9b23db as on 23rd May).

*However*, while testing this fix, I think I have uncovered a few more bugs(?)
with the +SETUPFILE interaction with the in-buffer tag selection.

Specifically, if the +SETUPFILE contains /any/ of the following
directives (not exhaustive, just what my setup happened to have), then
the tag listing in the completion buffer is showing _duplicated lists_
of the tags read from the setup file:

+STARTUP
+OPTIONS
+TYP_TODO
+CHOOSE_TODO

I have expanded the test case to include this scenario:

The setup file
==============