Revert "fetchFromGitHub: Revert to the original version"

This reverts commit 3d5391c256.

pkgs/top-level/all-packages.nix

@@ -203,11 +203,38 @@ with pkgs;
 
   fetchCrate = callPackage ../build-support/rust/fetchcrate.nix { };
 
-  fetchFromGitHub = { owner, repo, rev, sha256 }: fetchzip {
+  fetchFromGitHub = {
-    name = "source";
+    owner, repo, rev, name ? "source",
-    url = "https://github.com/${owner}/${repo}/archive/${rev}.zip";
+    fetchSubmodules ? false, private ? false,
-    inherit sha256;
+    githubBase ? "github.com", varPrefix ? null,
+    ... # For hash agility
+  }@args: assert private -> !fetchSubmodules;
+  let
+    baseUrl = "https://${githubBase}/${owner}/${repo}";
+    passthruAttrs = removeAttrs args [ "owner" "repo" "rev" "fetchSubmodules" "private" "githubBase" "varPrefix" ];
+    varBase = "NIX${if varPrefix == null then "" else "_${varPrefix}"}_GITHUB_PRIVATE_";
+    # We prefer fetchzip in cases we don't need submodules as the hash
+    # is more stable in that case.
+    fetcher = if fetchSubmodules then fetchgit else fetchzip;
+    privateAttrs = lib.optionalAttrs private {
+      netrcPhase = ''
+        if [ -z "''$${varBase}USERNAME" -o -z "''$${varBase}PASSWORD" ]; then
+          echo "Error: Private fetchFromGitHub requires the nix building process (nix-daemon in multi user mode) to have the ${varBase}USERNAME and ${varBase}PASSWORD env vars set." >&2
+          exit 1
+        fi
+        cat > netrc <<EOF
+        machine ${githubBase}
+                login ''$${varBase}USERNAME
+                password ''$${varBase}PASSWORD
+        EOF
+      '';
+      netrcImpureEnvVars = [ "${varBase}USERNAME" "${varBase}PASSWORD" ];
     };
+    fetcherArgs = (if fetchSubmodules
+        then { inherit rev fetchSubmodules; url = "${baseUrl}.git"; }
+        else ({ url = "${baseUrl}/archive/${rev}.tar.gz"; } // privateAttrs)
+      ) // passthruAttrs // { inherit name; };
+  in fetcher fetcherArgs // { meta.homepage = baseUrl; inherit rev; };
 
   fetchFromBitbucket = {
     owner, repo, rev, name ? "source",