File cppreference-doc-premailer-3.9-compat.patch of Package cppreference-doc

Index: cppreference-doc-20220730/commands/preprocess_cssless.py
===================================================================
--- cppreference-doc-20220730.orig/commands/preprocess_cssless.py
+++ cppreference-doc-20220730/commands/preprocess_cssless.py
@@ -72,8 +72,16 @@ def preprocess_html_merge_css(root, src_
 
     with warnings.catch_warnings():
         warnings.simplefilter("ignore")
-        premailer = Premailer(root, base_url=src_path,
-                              disable_link_rewrites=True, remove_classes=True)
+        try:
+            # Premailer >= 3.9
+            premailer = Premailer(root, base_url=src_path,
+                                  disable_link_rewrites=True, remove_classes=True,
+                                  allow_loading_external_files=True)
+        except:
+            # Premailer < 3.9
+            premailer = Premailer(root, base_url=src_path,
+                                  disable_link_rewrites=True, remove_classes=True)
+
         root = premailer.transform().getroot()
 
     return output.getvalue()