message: [Wallet] ensure CKeyMetadata.hdMasterKeyID will be cleared during SetNull()
diff: @@ -89,9 +89,8 @@ public:
  CKeyMetadata() { SetNull(); }
  CKeyMetadata(int64_t nCreateTime_)
  {
  - nVersion = CKeyMetadata::CURRENT_VERSION;
  + SetNull();
  nCreateTime = nCreateTime_;
  - hdKeypath.clear();
  }
  ADD_SERIALIZE_METHODS;
  @@ -113,6 +112,7 @@ public:
  nVersion = CKeyMetadata::CURRENT_VERSION;
  nCreateTime = 0;
  hdKeypath.clear();
  + hdMasterKeyID.SetNull();
  }
  };
  