previous hash added to GBT

src/rpc/core_rpc_server.cpp

@@ -475,6 +475,7 @@ namespace cryptonote
       LOG_ERROR("Failed to calculate offset for ");
       return false;
     }
+    res.prev_hash = string_tools::pod_to_hex(b.prev_id);
     res.blocktemplate_blob = string_tools::buff_to_hex_nodelimer(block_blob);
     res.status = CORE_RPC_STATUS_OK;
     return true;

src/rpc/core_rpc_server_commands_defs.h

@@ -383,6 +383,7 @@ namespace cryptonote
       uint64_t difficulty;
       uint64_t height;
       uint64_t reserved_offset;
+      std::string prev_hash;
       blobdata blocktemplate_blob;
       std::string status;
 
@@ -390,6 +391,7 @@ namespace cryptonote
         KV_SERIALIZE(difficulty)
         KV_SERIALIZE(height)
         KV_SERIALIZE(reserved_offset)
+        KV_SERIALIZE(prev_hash)
         KV_SERIALIZE(blocktemplate_blob)
         KV_SERIALIZE(status)
       END_KV_SERIALIZE_MAP()