patch 8.1.0042: if omni completion opens a window Insert mode is stopped

Problem:    If omni completion opens a window Insert mode is stopped.
            (Hirohito Higashi)
Solution:   Only set stop_insert_mode in a prompt buffer window.

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =

static int included_patches[] =
{   /* Add new patch number below this line */
/**/
    42,
/**/
    41,
/**/

src/window.c

@@ -2107,30 +2107,40 @@ win_equal_rec(
    static void
leaving_window(win_T *win)
{
    // Only matters for a prompt window.
    if (!bt_prompt(win->w_buffer))
	return;

    // When leaving a prompt window stop Insert mode and perhaps restart
    // it when entering that window again.
    win->w_buffer->b_prompt_insert = restart_edit;
    restart_edit = NUL;

    // When leaving the window (or closing the window) was done from a
    // callback we need to break out of the Insert mode loop.
    // callback we need to break out of the Insert mode loop and restart Insert
    // mode when entering the window again.
    if (State & INSERT)
    {
	stop_insert_mode = TRUE;
	if (bt_prompt(win->w_buffer) && win->w_buffer->b_prompt_insert == NUL)
	if (win->w_buffer->b_prompt_insert == NUL)
	    win->w_buffer->b_prompt_insert = 'A';
    }
}

    static void
entering_window(win_T *win)
{
    // Only matters for a prompt window.
    if (!bt_prompt(win->w_buffer))
	return;

    // When switching to a prompt buffer that was in Insert mode, don't stop
    // Insert mode, it may have been set in leaving_window().
    if (bt_prompt(win->w_buffer) && win->w_buffer->b_prompt_insert != NUL)
    if (win->w_buffer->b_prompt_insert != NUL)
	stop_insert_mode = FALSE;

    // When entering the prompt window may restart Insert mode.
    // When entering the prompt window restart Insert mode if we were in Insert
    // mode when we left it.
    restart_edit = win->w_buffer->b_prompt_insert;
}
#endif