Fix CurlDownloader requesting gzip encoding even though unsupported, fixes #10153

src/Composer/Util/Http/CurlDownloader.php

@@ -195,8 +195,9 @@ class CurlDownloader
         curl_setopt($curlHandle, CURLOPT_TIMEOUT, max((int) ini_get("default_socket_timeout"), 300));
         curl_setopt($curlHandle, CURLOPT_WRITEHEADER, $headerHandle);
         curl_setopt($curlHandle, CURLOPT_FILE, $bodyHandle);
-        curl_setopt($curlHandle, CURLOPT_ENCODING, "gzip");
+        curl_setopt($curlHandle, CURLOPT_ENCODING, ""); // let cURL set the Accept-Encoding header to what it supports
         curl_setopt($curlHandle, CURLOPT_PROTOCOLS, CURLPROTO_HTTP | CURLPROTO_HTTPS);
+
         if (function_exists('curl_share_init')) {
             curl_setopt($curlHandle, CURLOPT_SHARE, $this->shareHandle);
         }