patch 8.2.1999: terminal popup test sometimes fails

Problem:    Terminal popup test sometimes fails.
Solution:   Wait for the popup to close.

src/testdir/test_terminal.vim

@@ -1249,8 +1249,8 @@ func Test_terminal_popup_bufload()
   " must not have switched to another window
   call assert_equal(winid, win_getid())
 
-  call feedkeys("exit\<CR>", 'xt')
-  sleep 50m
+  call StopShellInTerminal(termbuf)
+  call WaitFor({-> win_getid() != winid})
   exe 'bwipe! ' .. newbuf
 endfunc
 

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1999,
 /**/
     1998,
 /**/