Add changelog item

Author: gumb0

CHANGELOG.md

@@ -27,7 +27,8 @@
 - Fixed: [#5581](https://github.com/ethereum/aleth/pull/5581) Fixed finding neighbour nodes in Discovery.
 - Fixed: [#5599](https://github.com/ethereum/aleth/pull/5600) Prevent aleth from attempting concurrent connection to node which results in disconnect of original connection.
 - Fixed: [#5609](https://github.com/ethereum/aleth/pull/5609) Log valid local enode-address when external IP is not known.
-- Fixed: [#5627](https://github.com/ethereum/aleth/pull/5627) Correct testeth --help log output indentation
+- Fixed: [#5627](https://github.com/ethereum/aleth/pull/5627) Correct testeth --help log output indentation.
+- Fixed: [#5647](https://github.com/ethereum/aleth/pull/5647) test_importRawBlock RPC method correctly fails in case of import failure.
 
 ## [1.6.0] - 2019-04-16