* lisp/ox.el (org-export-options-alist): New export option toggling
environment variable expansion in link paths.
(org-export-expand-links): New customization.
(org-export--expand-links): New function expanding environment
variables all the link paths in AST.
(org-export-expand-include-keyword):
(org-export--blindly-expand-include): Add new optional arguments to
expand environment variables in INCLUDE file paths. Update
docstrings.
(org-export--annotate-info): Call `org-export--expand-links' during
export and pass :expand-links parameter to
`org-export-expand-include-keyword'.
* doc/org-manual.org (Export Settings): Document the new option.
* etc/ORG-NEWS (New export option ~org-export-expand-links~): Announce
new option.
Link: https://list.orgmode.org/orgmode/87pm6fbnlo.fsf@localhost/
f409cb4e52