Updates hydra: 47077da Adds ChangeLog

diff --git a/hydra b/hydra
index 78dc21bfef3f76ccb8c35fc055daa9857ea8a196..47077daaec91ca2e078055891194680e5796462d 160000 (submodule)
--- a/hydra
+++ b/hydra
@@ -1 +1 @@
-Subproject commit 78dc21bfef3f76ccb8c35fc055daa9857ea8a196
+Subproject commit 47077daaec91ca2e078055891194680e5796462d