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/eval.c b/src/eval.c
index 06f3585..c104695 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -372,6 +372,7 @@
     {VV_NAME("true",		 VAR_SPECIAL), VV_RO},
     {VV_NAME("null",		 VAR_SPECIAL), VV_RO},
     {VV_NAME("none",		 VAR_SPECIAL), VV_RO},
+    {VV_NAME("vim_did_enter",	 VAR_NUMBER), VV_RO},
 };
 
 /* shorthand */