patch 9.0.0076: no test for what patch 8.1.1424 fixes

Problem:    No test for what patch 8.1.1424 fixes.
Solution:   Add a test. (closes #10789)
diff --git a/src/popupmenu.c b/src/popupmenu.c
index c030cc9..37c4a6d 100644
--- a/src/popupmenu.c
+++ b/src/popupmenu.c
@@ -1549,8 +1549,8 @@
 
 	c = vgetc();
 
-	// Bail out when typing Esc, CTRL-C or some callback closed the popup
-	// menu.
+	// Bail out when typing Esc, CTRL-C or some callback or <expr> mapping
+	// closed the popup menu.
 	if (c == ESC || c == Ctrl_C || pum_array == NULL)
 	    break;
 	else if (c == CAR || c == NL)
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index 5fb7e82..af14167 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -984,6 +984,25 @@
   endtry
 endfunc
 
+" This used to crash before patch 8.1.1424
+func Test_popup_delete_when_shown()
+  CheckFeature menu
+  CheckNotGui
+
+  func Func()
+    popup Foo
+    return "\<Ignore>"
+  endfunc
+
+  nmenu Foo.Bar :
+  nnoremap <expr> <F2> Func()
+  call feedkeys("\<F2>\<F2>\<Esc>", 'xt')
+
+  delfunc Func
+  nunmenu Foo.Bar
+  nunmap <F2>
+endfunc
+
 func Test_popup_complete_info_01()
   new
   inoremap <buffer><F5> <C-R>=complete_info().mode<CR>
diff --git a/src/version.c b/src/version.c
index 1909fd4..9081fec 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    76,
+/**/
     75,
 /**/
     74,