Merge pull request #3399 from freqtrade/fix_sell_rate_caching

[minor] Fix sell rate caching

freqtrade/freqtradebot.py

@@ -721,6 +721,9 @@ class FreqtradeBot:
                     raise PricingError from e
                 logger.debug(f"  order book {config_ask_strategy['price_side']} top {i}: "
                              f"{sell_rate:0.8f}")
+                # Assign sell-rate to cache - otherwise sell-rate is never updated in the cache,
+                # resulting in outdated RPC messages
+                self._sell_rate_cache[trade.pair] = sell_rate
 
                 if self._check_and_execute_sell(trade, sell_rate, buy, sell):
                     return True