patch 7.4.2006
Problem:    Crash when using tabnext in BufUnload autocmd. (Norio Takagi)
Solution:   First check that the current buffer is the right one. (Hirohito
            Higashi)
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 1dceb70..187d8d2 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -60,3 +60,21 @@
 
   augroup! test_bufunload_group
 endfunc
+
+" SEGV occurs in older versions.  (At least 7.4.2005 or older)
+function Test_autocmd_bufunload_with_tabnext()
+  tabedit
+  tabfirst
+
+  augroup test_autocmd_bufunload_with_tabnext_group
+    autocmd!
+    autocmd BufUnload <buffer> tabnext
+  augroup END
+
+  quit
+  call assert_equal(2, tabpagenr('$'))
+
+  augroup! test_autocmd_bufunload_with_tabnext_group
+  tablast
+  quit
+endfunc