From 425c7e46a00a9393ca3e63973dc08e655778da87 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Tue, 5 Aug 2025 09:21:41 +0100
Subject: [PATCH] fetchurl: fix `resolvedUrl` eval on URLs without mirror://
 prefix

Without the change `resolvedUrl` fails on non-mirror:// packages as:

    $ nix eval --impure --expr 'with import ./. {}; AMB-plugins.src.resolvedUrl'
    error:
       ...
       error: expected a list but found null: null

After ther change the eval works as expected:

    $ nix eval --impure --expr 'with import ./. {}; AMB-plugins.src.resolvedUrl'
    "http://kokkinizita.linuxaudio.org/linuxaudio/downloads/AMB-plugins-0.8.1.tar.bz2"
---
 pkgs/build-support/fetchurl/default.nix | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pkgs/build-support/fetchurl/default.nix b/pkgs/build-support/fetchurl/default.nix
index 6d86386e051a..049458a940c4 100644
--- a/pkgs/build-support/fetchurl/default.nix
+++ b/pkgs/build-support/fetchurl/default.nix
@@ -203,7 +203,10 @@ let
         else
           throw "unknown mirror:// site ${mirrorName}";
     in
-    if mirrorName == null then url else "${lib.head mirrorList}${lib.elemAt mirrorSplit 1}";
+    if mirrorSplit == null || mirrorName == null then
+      url
+    else
+      "${lib.head mirrorList}${lib.elemAt mirrorSplit 1}";
 in
 
 assert