vim-patch:9.1.1601: Patch v8.1.0425 was wrong

Problem:  Patch v8.1.0425 was wrong
Solution: Revert that patch (Hirohito Higashi)

This is because the root cause was fixed in 8.1.0786 and a regression
occurred elsewhere.

related: vim/vim#3455
related: vim/vim#3830
fixes: vim/vim#11558
closes: vim/vim#17899

6abe5e4904

Co-authored-by: Hirohito Higashi <h.east.727@gmail.com>
(cherry picked from commit 7230296bdb)

src/nvim/buffer.c

@@ -1728,9 +1728,6 @@ void enter_buffer(buf_T *buf)
   // mark cursor position as being invalid
   curwin->w_valid = 0;
 
-  buflist_setfpos(curbuf, curwin, curbuf->b_last_cursor.mark.lnum,
-                  curbuf->b_last_cursor.mark.col, true);
-
   // Make sure the buffer is loaded.
   if (curbuf->b_ml.ml_mfp == NULL) {    // need to load the file
     // If there is no filetype, allow for detecting one.  Esp. useful for

test/old/testdir/test_buffer.vim

@@ -609,4 +609,31 @@ func Test_closed_buffer_still_in_window()
   %bw!
 endfunc
 
+" Cursor position should be restored when switching to a buffer previously
+" viewed in a window, regardless of whether it's visible in another one.
+func Test_switch_to_previously_viewed_buffer()
+  set nostartofline
+  new Xviewbuf
+  call setline(1, range(1, 200))
+  let oldwin = win_getid()
+  vsplit
+
+  call cursor(100, 3)
+  edit Xotherbuf
+  buffer Xviewbuf
+  call assert_equal([0, 100, 3, 0], getpos('.'))
+
+  exe win_id2win(oldwin) .. 'close'
+  setlocal bufhidden=hide
+
+  call cursor(200, 3)
+  edit Xotherbuf
+  buffer Xviewbuf
+  call assert_equal([0, 200, 3, 0], getpos('.'))
+
+  bwipe! Xotherbuf
+  bwipe! Xviewbuf
+  set startofline&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab