vim-patch:7.4.423

Problem:    expand("$shell") does not work as documented.
Solution:   Do not escape the $ when expanding environment variables.

https://code.google.com/p/vim/source/detail?r=v7-4-423

src/nvim/version.c

@@ -306,7 +306,7 @@ static int included_patches[] = {
   //426 NA
   425,
   //424 NA
-  //423,
+  423,
   //422,
   421,
   //420 NA