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/main.c b/src/main.c
index 35c940f..91ef66d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -969,6 +969,9 @@
     if (p_im)
 	need_start_insertmode = TRUE;
 
+#ifdef FEAT_EVAL
+    set_vim_var_nr(VV_VIM_DID_ENTER, 1L);
+#endif
 #ifdef FEAT_AUTOCMD
     apply_autocmds(EVENT_VIMENTER, NULL, NULL, FALSE, curbuf);
     TIME_MSG("VimEnter autocommands");