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

It prevents the build system from issuing the repo sync that
requires git and an internet connection.

From: Lucio Sauer <watermanpaint@posteo.net>
--- a/build/configure/src/rust.rs
+++ b/build/configure/src/rust.rs
@@ -10,7 +10,7 @@ use ninja_gen::cargo::CargoClippy;
 use ninja_gen::cargo::CargoFormat;
 use ninja_gen::cargo::CargoTest;
 use ninja_gen::cargo::RustOutput;
-use ninja_gen::git::SyncSubmodule;
+use ninja_gen::git::SyncSubmoduleOffline;
 use ninja_gen::glob;
 use ninja_gen::hash::simple_hash;
 use ninja_gen::input::BuildInput;
@@ -27,15 +27,16 @@ pub fn build_rust(build: &mut Build) -> Result<()> {
 
 fn prepare_translations(build: &mut Build) -> Result<()> {
     // ensure repos are checked out
+    println!("Patch: Skipping git repository sync for translation files.");
     build.add_action(
         "ftl:repo:core",
-        SyncSubmodule {
+        SyncSubmoduleOffline {
             path: "ftl/core-repo",
         },
     )?;
     build.add_action(
         "ftl:repo:qt",
-        SyncSubmodule {
+        SyncSubmoduleOffline {
             path: "ftl/qt-repo",
         },
     )?;
--- a/build/ninja_gen/src/git.rs
+++ b/build/ninja_gen/src/git.rs
@@ -12,6 +12,10 @@ pub struct SyncSubmodule {
     pub path: &'static str,
 }
 
+pub struct SyncSubmoduleOffline {
+    pub path: &'static str,
+}
+
 impl BuildAction for SyncSubmodule {
     fn command(&self) -> &str {
         "git -c protocol.file.allow=always submodule update --init $path"
@@ -37,6 +41,17 @@ impl BuildAction for SyncSubmodule {
     }
 }
 
+impl BuildAction for SyncSubmoduleOffline {
+    fn command(&self) -> &str {
+        "echo Running SyncSubmoduleOffline stub function for $path"
+    }
+
+    fn files(&mut self, build: &mut impl build::FilesHandle) {
+        build.add_variable("path", self.path);
+        build.add_output_stamp(format!("git/{}", self.path));
+    }
+}
+
 /// We check the mtime of .git/HEAD to detect when we should sync submodules.
 /// If this repo is a submodule of another project, .git/HEAD will not exist,
 /// and we fall back on .git/modules/*/HEAD in a parent folder instead.