vim-patch:9.1.1407: Can't use getpos('v') in OptionSet when using setbufvar() (#34177)

Problem:  Can't use getpos('v') in OptionSet when using setbufvar().
Solution: Don't reset Visual selection when switching to the same
          buffer (zeertzjq).

closes: vim/vim#17373

5717ee33db
(cherry picked from commit bd01bd6564)

test/old/testdir/test_autocmd.vim

@@ -3458,6 +3458,28 @@ func Test_Visual_doautoall_redraw()
   %bwipe!
 endfunc
 
+func Test_get_Visual_selection_in_curbuf_autocmd()
+  throw 'Skipped: use test/functional/legacy/autocmd_spec.lua'
+  call test_override('starting', 1)
+  new
+  autocmd OptionSet list let b:text = getregion(getpos('.'), getpos('v'))
+  call setline(1, 'foo bar baz')
+
+  normal! gg0fbvtb
+  setlocal list
+  call assert_equal(['bar '], b:text)
+  exe "normal! \<Esc>"
+
+  normal! v0
+  call setbufvar('%', '&list', v:false)
+  call assert_equal(['foo bar '], b:text)
+  exe "normal! \<Esc>"
+
+  autocmd! OptionSet list
+  bwipe!
+  call test_override('starting', 0)
+endfunc
+
 " This was using freed memory.
 func Test_BufNew_arglocal()
   arglocal