fixed unexpected reflect behavior

After tls.Unmarshal() an empty slice is not assigned the nil value, but rather
a slice of zero length.  It is in contrast to NewTreeHeadV1(), which assigns a
nil value.  Therefore, reflect.DeepEqual() considers them to be different.

Fixed by assigning an empty tree head extension as `make([]byte, 0)`,
and not looking for nil values but rather zero-length values with len().

Further read: "Note that a non-nil empty slice and a nil slice [...] are
not deeply equal." (https://golang.org/pkg/reflect/#DeepEqual).

1 files changed, 1 insertions, 1 deletions

diff --git a/type.go b/type.go
index 72aeecc..db9ddc6 100644
--- a/type.go
+++ b/type.go
@@ -282,7 +282,7 @@ func NewTreeHeadV1(lr *types.LogRootV1) *TreeHeadV1 {
 		uint64(lr.TimestampNanos / 1000 / 1000),
 		uint64(lr.TreeSize),
 		NodeHash{lr.RootHash},
-		nil,
+		make([]byte, 0),
 	}
 }