Fix #66.

impl/memory/datastore_test.go

Index: impl/memory/datastore_test.go
diff --git a/impl/memory/datastore_test.go b/impl/memory/datastore_test.go
index c9580f0f7f1af8cad4585884b1ab52948557a426..045c8c37d1336f9e97b7972574585eabb1d2de1a 100644
--- a/impl/memory/datastore_test.go
+++ b/impl/memory/datastore_test.go
@@ -731,6 +731,32 @@ func TestDefaultTimeField(t *testing.T) {
 	})
 }
 
+// High level test for ancestor queries where the parent and child have
+// identical fields. There was a bug where it would accidentally load the parent
+// entity when attempt to query for the child.
+func TestAncestorChildFieldQuery(t *testing.T) {

[dnj, 2016/11/20 16:44:25]

Can this test be folded up into one of the "datastore_intex_*test" test cases?
Feels weird having it sit top-level.

+	ctx := Use(context.Background())
+	testable := ds.GetTestable(ctx)
+	testable.Consistent(true)
+	testable.AutoIndex(true)
+
+	type Parent struct {
+		_       int64 `gae:"$id,1"`
+		Created time.Time
+	}
+	p := Parent{}
+	if err := ds.Put(ctx, &p); err != nil {
+		t.Fatal(err)
+	}
+	// If you comment out the .Order part below, the test succeeds

[dnj, 2016/11/20 16:44:25]

This comment can be removed.

+	q := ds.NewQuery("notParent").Ancestor(ds.KeyForObj(ctx, &p)).Order("-Created")
+	if val, err := ds.Count(ctx, q); err != nil {
+		t.Fatal(err)
+	} else if val != 0 {
+		t.Fatalf("val: %d != 0", val)
+	}
+}
+
 func TestNewDatastore(t *testing.T) {
 	t.Parallel()