Use neat units rather than nanoseconds constant.

unionfs/autounion.go

@@ -82,7 +82,7 @@ func (me *AutoUnionFs) String() string {
 func (me *AutoUnionFs) OnMount(nodeFs *fuse.PathNodeFs) {
 	me.nodeFs = nodeFs
 	if me.options.UpdateOnMount {
-		time.AfterFunc(0.1e9, func() { me.updateKnownFses() })
+		time.AfterFunc(100 * time.Millisecond, func() { me.updateKnownFses() })
 	}
 }
 

unionfs/unionfs_test.go

@@ -701,7 +701,7 @@ func TestUnionFsTruncateTimestamp(t *testing.T) {
 	fn := wd + "/mnt/y"
 	err := ioutil.WriteFile(fn, []byte(contents), 0644)
 	CheckSuccess(err)
-	time.Sleep(0.2e9)
+	time.Sleep(200 * time.Millisecond)
 
 	truncTs := time.Now()
 	err = os.Truncate(fn, 3)