nixos/gitlab: Use Git 2.35.x to work around git bug (#177776)

Git 2.36.1 seemingly contains a commit-graph related bug which is
easily triggered through GitLab, so let's downgrade it to 2.35.x until
this issue is solved. See
https://gitlab.com/gitlab-org/gitlab/-/issues/360783#note_992870101.

nixos/modules/services/misc/gitlab.nix

@@ -13,6 +13,22 @@ let
                       else
                         pkgs.postgresql_12;
 
+  # Git 2.36.1 seemingly contains a commit-graph related bug which is
+  # easily triggered through GitLab, so we downgrade it to 2.35.x
+  # until this issue is solved. See
+  # https://gitlab.com/gitlab-org/gitlab/-/issues/360783#note_992870101.
+  gitPackage =
+    let
+      version = "2.35.3";
+    in
+      pkgs.git.overrideAttrs (oldAttrs: rec {
+        inherit version;
+        src = pkgs.fetchurl {
+          url = "https://www.kernel.org/pub/software/scm/git/git-${version}.tar.xz";
+          sha256 = "sha256-FenbT5vy7Z//MMtioAxcfAkBAV9asEjNtOiwTd7gD6I=";
+        };
+      });
+
   gitlabSocket = "${cfg.statePath}/tmp/sockets/gitlab.socket";
   gitalySocket = "${cfg.statePath}/tmp/sockets/gitaly.socket";
   pathUrlQuote = url: replaceStrings ["/"] ["%2F"] url;
@@ -41,7 +57,7 @@ let
     prometheus_listen_addr = "localhost:9236"
 
     [git]
-    bin_path = "${pkgs.git}/bin/git"
+    bin_path = "${gitPackage}/bin/git"
 
     [gitaly-ruby]
     dir = "${cfg.packages.gitaly.ruby}"
@@ -137,7 +153,7 @@ let
       };
       workhorse.secret_file = "${cfg.statePath}/.gitlab_workhorse_secret";
       gitlab_kas.secret_file = "${cfg.statePath}/.gitlab_kas_secret";
-      git.bin_path = "git";
+      git.bin_path = "${gitPackage}/bin/git";
       monitoring = {
         ip_whitelist = [ "127.0.0.0/8" "::1/128" ];
         sidekiq_exporter = {
@@ -1275,7 +1291,7 @@ in {
       });
       path = with pkgs; [
         postgresqlPackage
-        git
+        gitPackage
         ruby
         openssh
         nodejs
@@ -1306,7 +1322,7 @@ in {
       path = with pkgs; [
         openssh
         procps  # See https://gitlab.com/gitlab-org/gitaly/issues/1562
-        git
+        gitPackage
         cfg.packages.gitaly.rubyEnv
         cfg.packages.gitaly.rubyEnv.wrappedRuby
         gzip
@@ -1351,7 +1367,7 @@ in {
       partOf = [ "gitlab.target" ];
       path = with pkgs; [
         exiftool
-        git
+        gitPackage
         gnutar
         gzip
         openssh
@@ -1412,7 +1428,7 @@ in {
       environment = gitlabEnv;
       path = with pkgs; [
         postgresqlPackage
-        git
+        gitPackage
         openssh
         nodejs
         procps