patch 7.4.1658
Problem:    A plugin does not know when VimEnter autocommands were already
            triggered.
Solution:   Add the v:vim_did_enter variable.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
new file mode 100644
index 0000000..12c9848
--- /dev/null
+++ b/src/testdir/test_autocmd.vim
@@ -0,0 +1,8 @@
+" Tests for autocommands
+
+func Test_vim_did_enter()
+  call assert_false(v:vim_did_enter)
+
+  " This script will never reach the main loop, can't check if v:vim_did_enter
+  " becomes one.
+endfunc