Respect git's ignore rules pervasively in pub.

sdk/lib/_internal/pub/test/serve/does_not_serve_gitignored_assets_in_a_path_dependency_test.dart

Index: sdk/lib/_internal/pub/test/serve/does_not_serve_gitignored_assets_in_a_path_dependency_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/does_not_serve_gitignored_assets_in_a_path_dependency_test.dart b/sdk/lib/_internal/pub/test/serve/does_not_serve_gitignored_assets_in_a_path_dependency_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..d92eb261bbf94e379556cea5b4c3a588232a91f1
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/serve/does_not_serve_gitignored_assets_in_a_path_dependency_test.dart
@@ -0,0 +1,38 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library pub_tests;
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+import 'utils.dart';
+
+main() {
+  initConfig();
+  integration("doesn't serve .gitignored assets in a path dependency", () {
+    ensureGit();
+
+    d.dir(appPath, [
+      d.appPubspec({"foo": {"path": "../foo"}}),
+    ]).create();
+
+    d.git("foo", [
+      d.libPubspec("foo", "1.0.0"),
+      d.dir("lib", [
+        d.file("outer.txt", "outer contents"),
+        d.file("visible.txt", "visible"),
+        d.dir("dir", [
+          d.file("inner.txt", "inner contents"),
+        ])
+      ]),
+      d.file(".gitignore", "/lib/outer.txt\n/lib/dir")
+    ]).create();
+
+    pubServe(shouldGetFirst: true);
+    requestShould404("packages/foo/outer.txt");
+    requestShould404("packages/foo/dir/inner.txt");
+    requestShouldSucceed("packages/foo/visible.txt", "visible");
+    endPubServe();
+  });
+}