Reuse Windows update source cache

tests/release_scripts.rs

@@ -95,6 +95,20 @@ fn installers_refuse_prebuilts_without_checksums() {
     );
 }
 
+#[test]
+fn windows_installer_reuses_persistent_source_update_cache() {
+    let ps1 = include_str!("../install.ps1");
+    assert!(ps1.contains("DOSH_UPDATE_CACHE"));
+    assert!(ps1.contains("$sourceCache = Assert-SafeUpdateCache $UpdateCache"));
+    assert!(ps1.contains("git -C $sourceCache fetch --depth 1 origin main"));
+    assert!(ps1.contains("git -C $sourceCache checkout -q -B main FETCH_HEAD"));
+    assert!(ps1.contains("git clone --depth 1 --branch main $Repo $sourceCache"));
+    assert!(
+        !ps1.contains("git clone --depth 1 $Repo $tmp"),
+        "Windows source updates should reuse a persistent cache instead of recloning into temp"
+    );
+}
+
 #[test]
 fn package_check_verifies_only_artifacts_it_builds() {
     let makefile = include_str!("../Makefile");