Don't reset the screen after emitting a BEL

Fixes #3693

src/reader.cpp

@@ -1438,6 +1438,9 @@ static void reader_flash() {
 
     reader_repaint();
     ignore_result(write(STDOUT_FILENO, "\a", 1));
+    // The write above changed the timestamp of stdout; ensure we don't therefore reset our screen.
+    // See #3693.
+    s_save_status(&data->screen);
 
     pollint.tv_sec = 0;
     pollint.tv_nsec = 100 * 1000000;

src/screen.cpp

@@ -352,7 +352,7 @@ static size_t calc_prompt_lines(const wcstring &prompt) {
 
 /// Stat stdout and stderr and save result. This should be done before calling a function that may
 /// cause output.
-static void s_save_status(screen_t *s) {
+void s_save_status(screen_t *s) {
     fstat(1, &s->prev_buff_1);
     fstat(2, &s->prev_buff_2);
 }

src/screen.h

@@ -181,6 +181,9 @@ void s_write(screen_t *s, const wcstring &left_prompt, const wcstring &right_pro
 /// line of garbage for every repaint, which will quickly fill the screen.
 void s_reset(screen_t *s, bool reset_cursor, bool reset_prompt = true);
 
+/// Stat stdout and stderr and save result as the current timestamp.
+void s_save_status(screen_t *s);
+
 enum screen_reset_mode_t {
     /// Do not make a new line, do not repaint the prompt.
     screen_reset_current_line_contents,