Allow inheritance of date and slug properties

ox-hugo.el

@@ -2938,6 +2938,8 @@ are \"toml\" and \"yaml\"."
                      "HUGO_WITH_LOCALE"
                      "HUGO_LOCALE"
                      "HUGO_PAIRED_SHORTCODES"
+                     "DATE" ;Useful for inheriting same date to same posts in different languages
+                     "HUGO_SLUG" ;Useful for inheriting same slug to same posts in different languages
                      "HUGO_AUTO_SET_LASTMOD")))
     (mapcar (lambda (str)
               (concat "EXPORT_" str))

test/site/content-org/all-posts.org

@@ -4497,6 +4497,29 @@ This post will have the =foo= key in front-matter replaced with
 :END:
 Here, attempt is made to replace a non-existing key =toto=, but still,
 there shouldn't be any error.
+* Date and slug inheritance                           :inheritance:date:slug:
+:PROPERTIES:
+:EXPORT_DATE: 2018-02-12
+:EXPORT_HUGO_SLUG: data-and-slug-inheritance
+:END:
+** Date and slug inheritance (English)
+:PROPERTIES:
+:EXPORT_HUGO_SECTION: posts/en
+:EXPORT_FILE_NAME: date-and-slug-inheritance.en.md
+:END:
+Date and slug inheritance is useful when you want to use the same data
+and slug for multiple posts, but in different languages.
+
+[[/posts/es/data-and-slug-inheritance][Spanish version]]
+** Date and slug inheritance (Spanish)
+:PROPERTIES:
+:EXPORT_HUGO_SECTION: posts/es
+:EXPORT_FILE_NAME: date-and-slug-inheritance.es.md
+:END:
+La herencia de fecha y slug es útil cuando desea usar los mismos datos
+y slug para múltiples publicaciones, pero en diferentes idiomas.
+
+[[/posts/en/data-and-slug-inheritance][English version]]
 * Real Examples                                               :real_examples:
 :PROPERTIES:
 :EXPORT_HUGO_SECTION: real-examples

test/site/content/posts/en/date-and-slug-inheritance.en.md

@@ -0,0 +1,12 @@
++++
+title = "Date and slug inheritance (English)"
+date = 2018-02-12
+slug = "data-and-slug-inheritance"
+tags = ["inheritance", "date", "slug"]
+draft = false
++++
+
+Date and slug inheritance is useful when you want to use the same data
+and slug for multiple posts, but in different languages.
+
+[Spanish version](/posts/es/data-and-slug-inheritance)

test/site/content/posts/es/date-and-slug-inheritance.es.md

@@ -0,0 +1,12 @@
++++
+title = "Date and slug inheritance (Spanish)"
+date = 2018-02-12
+slug = "data-and-slug-inheritance"
+tags = ["inheritance", "date", "slug"]
+draft = false
++++
+
+La herencia de fecha y slug es útil cuando desea usar los mismos datos
+y slug para múltiples publicaciones, pero en diferentes idiomas.
+
+[English version](/posts/en/data-and-slug-inheritance)

test/site/themes/bare_min

@@ -1 +1 @@
-Subproject commit 46bbd294e1109fc0368b2cfdadc6af020ba5d19e
+Subproject commit 4e952f997f16a7a2fcbc68b538a74f69921c3b5d