fix: og:image will be incorrect if the image uses a cross-domain URL

Author: cotes2020

_includes/head.html

@@ -24,20 +24,25 @@
 
   {% if page.image %}
     {% assign img = page.image.path | default: page.image %}
-    {% assign img_path = page.img_path | append: '/' | append: img | replace: '//', '/' %}
-    {% capture target %}"{{ img | absolute_url }}"{% endcapture %}
-
-    {% if site.img_cdn contains '//' %}
-      <!-- it's a cross-origin URL -->
-      {% capture replacement %}"{{ site.img_cdn }}{{ img_path }}"{% endcapture %}
-    {% else %}
-      <!-- it's a local file path -->
-      {%- capture replacement -%}
-        "{{ site.img_cdn | append: '/' | append: img_path | replace: '//', '/' | absolute_url }}"
-      {%- endcapture -%}
-    {% endif %}
 
-    {% assign seo_tags = seo_tags | replace: target, replacement %}
+    {% unless img contains '://' %}
+      {% assign img_path = page.img_path | append: '/' | append: img | replace: '//', '/' %}
+      {% capture target %}"{{ img | absolute_url }}"{% endcapture %}
+
+      {% if site.img_cdn contains '//' %}
+        <!-- it's a cross-origin URL -->
+        {% capture replacement %}"{{ site.img_cdn }}{{ img_path }}"{% endcapture %}
+      {% else %}
+        <!-- it's a local file path -->
+        {%- capture replacement -%}
+          "{{ site.img_cdn | append: '/' | append: img_path | replace: '//', '/' | absolute_url }}"
+        {%- endcapture -%}
+      {% endif %}
+
+      {% assign seo_tags = seo_tags | replace: target, replacement %}
+
+    {% endunless %}
+
   {% endif %}
 
   {{ seo_tags }}