Fixed data races

src/block_template.cpp

@@ -115,7 +115,7 @@ BlockTemplate& BlockTemplate::operator=(const BlockTemplate& b)
 	m_extraNonceOffsetInTemplate = b.m_extraNonceOffsetInTemplate;
 	m_numTransactionHashes = b.m_numTransactionHashes;
 	m_prevId = b.m_prevId;
-	m_height = b.m_height;
+	m_height = b.m_height.load();
 	m_difficulty = b.m_difficulty;
 	m_seedHash = b.m_seedHash;
 	m_timestamp = b.m_timestamp;