Ignore manifest.xml for timestamp updates.

Change-Id: I8b58f739c91e4c4c6e4d5389b27b544963c0c235
diff --git a/cmd/gitfs-populate/main.go b/cmd/gitfs-populate/main.go
index 33c00b0..737a4c8 100644
--- a/cmd/gitfs-populate/main.go
+++ b/cmd/gitfs-populate/main.go
@@ -224,6 +224,9 @@
 	data := make([]byte, 1024)
 
 	if err := filepath.Walk(dir, func(n string, fi os.FileInfo, err error) error {
+		if n == filepath.Join(dir, "manifest.xml") {
+			return nil
+		}
 		if fi.Mode()&os.ModeType != 0 {
 			return nil
 		}
diff --git a/cmd/gitfs-populate/main_test.go b/cmd/gitfs-populate/main_test.go
index 1437b74..6a4159f 100644
--- a/cmd/gitfs-populate/main_test.go
+++ b/cmd/gitfs-populate/main_test.go
@@ -149,8 +149,10 @@
 
 func TestChangedFiles(t *testing.T) {
 	dir, err := createFSTree([]string{
+		"r1/manifest.xml",
 		"r1/a",
 		"r1/b",
+		"r2/manifest.xml",
 		"r2/a",
 		"r2/b",
 		"r2/c",
@@ -160,8 +162,10 @@
 	}
 
 	ck2 := "3f75526aa8f01eea5d76cee10722195dc73676df"
-	if err := syscall.Setxattr(filepath.Join(dir, "r2/b"), attr, []byte(ck2), 0); err != nil {
-		t.Fatalf("Setxattr: %v", err)
+	for _, changed := range []string{"r2/b", "r2/manifest.xml"} {
+		if err := syscall.Setxattr(filepath.Join(dir, changed), attr, []byte(ck2), 0); err != nil {
+			t.Fatalf("Setxattr: %v", err)
+		}
 	}
 
 	got, err := changedFiles(filepath.Join(dir, "r1"), filepath.Join(dir, "r2"))