Fix misfire of QuickFixCmdPre

Author: tpope

autoload/rails.vim

@@ -88,7 +88,7 @@ endfunction
 
 function! s:push_chdir(...)
   if !exists("s:command_stack") | let s:command_stack = [] | endif
-  if exists("b:rails_root") && a:0 ? getcwd() !=# rails#app().path() : !s:startswith(getcwd(), rails#app().path())
+  if exists("b:rails_root") && (a:0 ? getcwd() !=# rails#app().path() : !s:startswith(getcwd(), rails#app().path()))
     let chdir = exists("*haslocaldir") && haslocaldir() ? "lchdir " : "chdir "
     call add(s:command_stack,chdir.s:escarg(getcwd()))
     exe chdir.s:escarg(rails#app().path())