patch 9.2.0533: '[ mark moved to end of inserted text after CTRL-R CTRL-P paste

Problem:  After CTRL-R CTRL-P (or CTRL-R CTRL-O) pastes a register
          into Insert mode, a follow-up edit such as backspace makes
          stop_arrow() rewrite Insstart with the post-paste cursor
          position.  As a result the '[ mark points at the end of the
          inserted text instead of its start  (agguser, after 9.2.0384)
Solution: In stop_arrow(), only pull Insstart back when the cursor
          moved above the previous Insstart, so a line-start backspace
          can still save the joined range (#20031) without disturbing
          the start position for inserts that advance the cursor
          (Hirohito Higashi).

related: #20031
fixes:   #20130
closes:  #20322

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/edit.c

@@ -2512,11 +2512,16 @@ stop_arrow(void)
     {
 	if (u_save_cursor() == OK)
 	{
-	    // A command or event may have moved the cursor or edited the
-	    // buffer. Update Insstart so that later edits can properly decide
-	    // whether an extra undo entry is needed.
-	    Insstart = curwin->w_cursor;
-	    Insstart_textlen = (colnr_T)linetabsize_str(ml_get_curline());
+	    // A command or event may have moved the cursor before the next
+	    // edit. Pull Insstart back only when the cursor moved above it,
+	    // so that later edits can properly decide whether an extra undo
+	    // entry is needed. Advancing Insstart would mis-place '[ after a
+	    // register paste.
+	    if (LT_POS(curwin->w_cursor, Insstart))
+	    {
+		Insstart = curwin->w_cursor;
+		Insstart_textlen = (colnr_T)linetabsize_str(ml_get_curline());
+	    }
 	    ins_need_undo = FALSE;
 	}
     }

src/testdir/test_edit.vim

@@ -2482,4 +2482,18 @@ func Test_autoindent_no_strip_after_cursorholdi()
   bwipe!
 endfunc
 
+" Issue #20130: '[ must mark the start of the paste after CTRL-R CTRL-P + edit.
+func Test_open_square_mark_after_ctrl_r_ctrl_p_paste()
+  new
+  call setline(1, ['a', 'b', 'c', 'd'])
+  call cursor(4, 1)
+
+  call feedkeys("Vggyjo\<C-r>\<C-p>\"\<BS>\<Esc>", 'xt')
+
+  call assert_equal(['a', 'b', 'a', 'b', 'c', 'd', 'c', 'd'],
+        \ getline(1, '$'))
+  call assert_equal([0, 3, 1, 0], getpos("'["))
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    533,
 /**/
     532,
 /**/