This is an adapted patch from the games/anki FreeBSD port.
https://github.com/freebsd/freebsd-ports/blob/109c3d4629b84972e660b689d169ac0761c1a519/games/anki/files/patch-build_runner_src_build.rs

It adapts the ninja(-compatible) build system to the Gentoo system and
prevents repo sync via git.
* Mimic ninja-utils.eclass behavior to respect NINJA_VERBOSE.
  Can also be implemented in the ebuild via runner args when the rest
  of the patch gets dropped.
* Respect NINJA_STATUS if already set.
* Respect app-alternatives/ninja symlink (n2 is not yet in the tree).
  This is a workaround. A proper implementation similar to
  the LTO implementation (c6f429) should allow the build system to be set at
  configure time.

From: Lucio Sauer <watermanpaint@posteo.net>
--- a/build/ninja_gen/src/build.rs
+++ b/build/ninja_gen/src/build.rs
@@ -49,7 +49,7 @@ impl Build {
             output_text: Default::default(),
             action_names: Default::default(),
             groups: Default::default(),
-            have_n2: which::which("n2").is_ok(),
+            have_n2: false,
         };
 
         build.add_action("build:configure", ConfigureBuild {})?;
--- a/build/runner/src/build.rs
+++ b/build/runner/src/build.rs
@@ -56,11 +56,15 @@ pub fn run_build(args: BuildArgs) {
 
     let start_time = Instant::now();
     let mut command = Command::new(get_ninja_command());
+
+    if env::var("NINJA_VERBOSE").unwrap_or(String::from("ON")).eq("ON") {
+            command.arg("-v");
+    }
+
     command
         .arg("-f")
         .arg(&build_file)
         .args(ninja_args)
-        .env("NINJA_STATUS", "[%f/%t; %r active; %es] ")
         .env("PATH", &path)
         .env(
             "MYPY_CACHE_DIR",
@@ -75,6 +79,11 @@ pub fn run_build(args: BuildArgs) {
         // Updating svelte-check or its deps will likely remove the need for it.
         .env("NODE_OPTIONS", "--no-experimental-fetch");
 
+        if env::var("NINJA_STATUS").is_err() {
+            command.env("NINJA_STATUS", "[%f/%t; %r active; %es] ");
+        }
+
+
     // run build
     let mut status = command.status().expect("ninja not installed");
     if !status.success() && Instant::now().duration_since(start_time).as_secs() < 3 {
@@ -109,11 +118,7 @@ pub fn run_build(args: BuildArgs) {
 }
 
 fn get_ninja_command() -> &'static str {
-    if which::which("n2").is_ok() {
-        "n2"
-    } else {
-        "ninja"
-    }
+    "ninja"
 }
 
 fn setup_build_root() -> Utf8PathBuf {
@@ -154,8 +159,9 @@ fn bootstrap_build() {
 
 fn maybe_update_buildhash(build_root: &Utf8Path) {
     // only updated on release builds
+    println!("Patch: Skipping buildhash update if {build_root}/buildhash exists.");
     let path = build_root.join("buildhash");
-    if env::var("RELEASE").is_ok() || !path.exists() {
+    if !path.exists() {
         write_if_changed(&path, &get_buildhash())
     }
 }