blockchain: fix long term block weight for regtest mode

src/cryptonote_core/blockchain.cpp

@@ -3665,13 +3665,21 @@ bool Blockchain::update_next_cumulative_weight_limit(uint64_t *long_term_effecti
   {
     const uint64_t block_weight = m_db->get_block_weight(db_height - 1);
 
-    std::vector<uint64_t> weights;
-    const uint64_t nblocks = std::min<uint64_t>(m_long_term_block_weights_window, db_height);
-    weights.resize(nblocks);
-    for (uint64_t h = 0; h < nblocks; ++h)
-      weights[h] = m_db->get_block_long_term_weight(db_height - nblocks + h - 1);
-    std::vector<uint64_t> new_weights = weights;
-    uint64_t long_term_median = epee::misc_utils::median(weights);
+    std::vector<uint64_t> weights, new_weights;
+    uint64_t long_term_median;
+    if (db_height == 1)
+    {
+      long_term_median = CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V5;
+    }
+    else
+    {
+      const uint64_t nblocks = std::min<uint64_t>(m_long_term_block_weights_window, db_height - 1);
+      weights.resize(nblocks);
+      for (uint64_t h = 0; h < nblocks; ++h)
+        weights[h] = m_db->get_block_long_term_weight(db_height - nblocks + h);
+      new_weights = weights;
+      long_term_median = epee::misc_utils::median(weights);
+    }
     m_long_term_effective_median_block_weight = std::max<uint64_t>(CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V5, long_term_median);
 
     uint64_t short_term_constraint = m_long_term_effective_median_block_weight + m_long_term_effective_median_block_weight * 2 / 5;