Workaround for URI.merge/2 bug https://github.com/elixir-lang/elixir/issues/10771

If we avoid URI.merge unless we know we need it we reduce the edge cases we could encounter.
The site would need to both have "//" in the %URI{:path} and the image needs to be a relative URL.

lib/pleroma/web/mastodon_api/views/status_view.ex

@@ -380,9 +380,15 @@ def render("card.json", %{rich_media: rich_media, page_url: page_url}) do
     page_url = page_url_data |> to_string
 
     image_url =
-      if is_binary(rich_media["image"]) do
-        URI.merge(page_url_data, URI.parse(rich_media["image"]))
-        |> to_string
+      cond do
+        !is_binary(rich_media["image"]) ->
+          nil
+
+        String.starts_with?(rich_media["image"], "http") ->
+          rich_media["image"]
+
+        true ->
+          URI.merge(page_url_data, URI.parse(rich_media["image"])) |> to_string
       end
 
     %{