vim-patch: 7.4.381

Problem:    Get u_undo error when backspacing in Insert mode deletes more than
            one line break. (Ayberk Ozgur)
Solution:   Also decrement Insstart.lnum.

https://code.google.com/p/vim/source/detail?r=v7-4-381

src/nvim/version.c

@@ -214,7 +214,7 @@ static int included_patches[] = {
   //384 NA
   //383,
   //382,
-  //381,
+  381,
   //380 NA
   //379,
   //378,