Backport #8756 for v4.2.x: Respect collections_dir config within incl…

…ude tag (#8794)

Respect collections_dir config within include tag
This backports aa9a416 and 1aea158 to 4.2-stable

features/incremental_rebuild.feature

@@ -67,6 +67,25 @@ Feature: Incremental rebuild
     And the _site directory should exist
     And I should see "Basic Site with include tag: Regenerated by Jekyll" in "_site/index.html"
 
+  Scenario: Rebuild when a dependency of document in custom collection_dir is changed
+    Given I have a _includes directory
+    And I have a configuration file with "collections_dir" set to "collections"
+    And I have a collections/_posts directory
+    And I have the following post within the "collections" directory:
+      | title    | date       | layout  | content                                               |
+      | Wargames | 2009-03-27 | default | Basic Site with include tag: {% include about.html %} |
+    And I have an "_includes/about.html" file that contains "Generated by Jekyll"
+    When I run jekyll build -I
+    Then I should get a zero exit status
+    And the _site directory should exist
+    And I should see "Basic Site with include tag: Generated by Jekyll" in "_site/2009/03/27/wargames.html"
+    When I wait 1 second
+    Then I have an "_includes/about.html" file that contains "Regenerated by Jekyll"
+    When I run jekyll build -I
+    Then I should get a zero exit status
+    And the _site directory should exist
+    And I should see "Basic Site with include tag: Regenerated by Jekyll" in "_site/2009/03/27/wargames.html"
+
   Scenario: A themed-site and incremental regeneration
     Given I have a configuration file with "theme" set to "test-theme"
     And I have an "index.md" page that contains "Themed site"

lib/jekyll/tags/include.rb

@@ -234,12 +234,17 @@ def realpath_prefixed_with?(path, dir)
       end
 
       def add_include_to_dependency(inclusion, context)
-        return unless context.registers[:page]&.key?("path")
+        page = context.registers[:page]
+        return unless page&.key?("path")
+
+        absolute_path = \
+          if page["collection"]
+            @site.in_source_dir(@site.config["collections_dir"], page["path"])
+          else
+            @site.in_source_dir(page["path"])
+          end
 
-        @site.regenerator.add_dependency(
-          @site.in_source_dir(context.registers[:page]["path"]),
-          inclusion.path
-        )
+        @site.regenerator.add_dependency(absolute_path, inclusion.path)
       end
     end