neovim/neovim — pull request #1184 by Shougo (2014-09-16 10:37:44+00:00)
Title: [RFC] vim-patch:7.4.369

7.4.369:

> Problem: Using freed memory when exiting while compiled with EXITFREE.
> Solution: Set curwin to NULL and check for that. (Dominique Pelle)

https://code.google.com/p/vim/source/detail?r=v7-4-369

Original code in neovim uses `if (buf->b_signlist == NULL)` instead of `if (buf->b_signlist != NULL)`.
It seems bug...