Detect broken packagist.org mirrors and fix them on the fly, refs #9297

src/Composer/Repository/ComposerRepository.php

@@ -866,6 +866,12 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
             $this->hasPartialPackages = !empty($data['packages']) && is_array($data['packages']);
         }
 
+        // Horrible hack to workaround https://github.com/composer/composer/issues/9297 and bad mirrors, should be disabled if possible once they fix things
+        if (!empty($data['metadata-url']) && !empty($data['list']) && $data['metadata-url'] === '/p/%package%.json' && $data['list'] === 'https://packagist.org/packages/list.json') {
+            file_put_contents('php://stderr', 'Composer 2 repository support for '.$this->url.' has been disabled due to what seems like a misconfiguration. If this is a packagist.org mirror we recommend removing it as Composer 2 handles network operations much faster and should work fine without.'.PHP_EOL);
+            unset($data['metadata-url']);
+        }
+
         // metadata-url indicates V2 repo protocol so it takes over from all the V1 types
         // V2 only has lazyProviders and possibly partial packages, but no ability to process anything else,
         // V2 also supports async loading