unstableGitUpdater: fix updating fetchzip-based sources

a67950f20b added `url` attribute
from `fetchurl` and therefore also from `fetchzip`.
We previously relied on `url` from fetchgit-based fetchers
to find the repo URL but now it will just return tarballs
in the case of `fetchFrom{GitHub,GitLab}`.

Let’s add an attribute to `fetch{git,FromGitHub,FromGitLab}`
to expose a repo URL consistently.

pkgs/build-support/fetchgit/default.nix

@@ -92,4 +92,8 @@ stdenvNoCC.mkDerivation {
   ];
 
   inherit preferLocalBuild meta;
+
+  passthru = {
+    gitRepoUrl = url;
+  };
 }

pkgs/build-support/fetchgithub/default.nix

@@ -42,11 +42,20 @@ let
     '';
     netrcImpureEnvVars = [ "${varBase}USERNAME" "${varBase}PASSWORD" ];
   };
+
+  gitRepoUrl = "${baseUrl}.git";
+
   fetcherArgs = (if useFetchGit
     then {
-      inherit rev deepClone fetchSubmodules sparseCheckout; url = "${baseUrl}.git";
+      inherit rev deepClone fetchSubmodules sparseCheckout; url = gitRepoUrl;
     } // lib.optionalAttrs (leaveDotGit != null) { inherit leaveDotGit; }
-    else { url = "${baseUrl}/archive/${rev}.tar.gz"; }
+    else {
+      url = "${baseUrl}/archive/${rev}.tar.gz";
+
+      passthru = {
+        inherit gitRepoUrl;
+      };
+    }
   ) // privateAttrs // passthruAttrs // { inherit name; };
 in
 

pkgs/build-support/fetchgitlab/default.nix

@@ -15,11 +15,17 @@ let
   useFetchGit = deepClone || fetchSubmodules || leaveDotGit;
   fetcher = if useFetchGit then fetchgit else fetchzip;
 
+  gitRepoUrl = "${protocol}://${domain}/${slug}.git";
+
   fetcherArgs = (if useFetchGit then {
     inherit rev deepClone fetchSubmodules leaveDotGit;
-    url = "${protocol}://${domain}/${slug}.git";
+    url = gitRepoUrl;
   } else {
     url = "${protocol}://${domain}/api/v4/projects/${escapedSlug}/repository/archive.tar.gz?sha=${escapedRev}";
+
+    passthru = {
+      inherit gitRepoUrl;
+    };
   }) // passthruAttrs // { inherit name; };
 in
 

pkgs/common-updater/unstable-updater.nix

@@ -49,7 +49,7 @@ let
     # By default we set url to src.url
     if [[ -z "$url" ]]; then
         url="$(${nix}/bin/nix-instantiate $systemArg --eval -E \
-                   "with import ./. {}; $UPDATE_NIX_ATTR_PATH.src.url or $UPDATE_NIX_ATTR_PATH.src.meta.homepage" \
+                   "with import ./. {}; $UPDATE_NIX_ATTR_PATH.src.gitRepoUrl" \
             | tr -d '"')"
     fi