Org-mode compilation fails with the following errors if emacs-25.2.2 is
used (Ubuntu-18.04 LTS bionic)
Compiling /home/ubuntu/org-mode/lisp/ox-ascii.el...
In toplevel form:
ox-ascii.el:31:1:Error: Cannot open load file: No such file or directory, xdg
Compiling /home/ubuntu/org-mode/lisp/ox-beamer.el...
In toplevel form:
ox-beamer.el:34:1:Error: Cannot open load file: No such file or directory, xdg
>
> ...
org.el in the main branch still declares
;; Package-Requires: ((emacs "25.1"))
but it seems xdg.el used by org-persist.el was added in emacs-26.0.
I do not actually use emacs-25.2, but it happened that I have a test
container for Org based on Ubuntu-18.04.
Either org-persist and org-compat should be updated with some
compatibility code or required emacs version should be updated once more.
