Avoid caching resource when called via `include_relative` tag (#9784)

Merge pull request 9784

features/include_relative_tag.feature

@@ -58,3 +58,22 @@ Feature: include_relative Tag
     Then I should get a zero exit status
     And the _site directory should exist
     And I should see "Welcome back Dear Reader!" in "_site/index.html"
+
+  Scenario: Include multiple files relative to a page at root
+    Given I have an "apple.md" page with foo "bar" that contains "{{ page.path }}, {{ page.foo }}"
+    And I have an "banana.md" page with content:
+      """
+        {% include_relative apple.md %}
+        {% include_relative cherry.md %}
+
+        {{ page.path }}
+      """
+    And I have an "cherry.md" page with foo "lipsum" that contains "{{ page.path }}, {{ page.foo }}"
+    When I run jekyll build
+    Then I should get a zero exit status
+    And the _site directory should exist
+    And I should see "<p>apple.md, bar</p>" in "_site/apple.html"
+    And I should see "<hr />\n<p>foo: bar" in "_site/banana.html"
+    And I should see "<hr />\n<p>foo: lipsum" in "_site/banana.html"
+    And I should see "<p>cherry.md, lipsum</p>" in "_site/cherry.html"
+    But I should not see "foo: lipsum" in "_site/cherry.html"

lib/jekyll/tags/include.rb

@@ -249,6 +249,11 @@ module Jekyll
     end
 
     class IncludeRelativeTag < IncludeTag
+      def load_cached_partial(path, context)
+        context.registers[:cached_partials] ||= {}
+        context.registers[:cached_partials][path] ||= parse_partial(path, context)
+      end
+
       def tag_includes_dirs(context)
         Array(page_path(context)).freeze
       end
@@ -267,6 +272,17 @@ module Jekyll
         path = File.join(site.config["collections_dir"], path) if page["collection"]
         path.delete_suffix("/#excerpt")
       end
+
+      # Since Jekyll 4 caches convertibles based on their path within the only instance of
+      # `LiquidRenderer`, initialize a new LiquidRenderer instance on every render of this
+      # tag to bypass caching rendered output of page / document.
+      def parse_partial(path, context)
+        LiquidRenderer.new(context.registers[:site]).file(path).parse(read_file(path, context))
+      rescue Liquid::Error => e
+        e.template_name = path
+        e.markup_context = "included " if e.markup_context.nil?
+        raise e
+      end
     end
   end
 end