bug#37258: 27.0.50; custom-theme-directory variable is set to nil before init.el loads causing load-theme to fail

[Eli Zaretskii]

> From: Wojciech Kozlowski <wk@wojciechkozlowski.eu>
> Date: Sun, 01 Sep 2019 18:40:53 +0200
> 
> My init.el fails on the call to load-path leaving the following
> backtrace (from the point load-theme is called):
> 
> Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>   file-directory-p(nil)
>   custom-theme--load-path()
>   load-theme(havoc-dark t)
> 
> Digging deeper, this is caused by the fact that the variable `custom-
> theme-directory' has been reset to nil.

Please try again with the latest master, I think Paul has just fixed
this.