caches: pass synchronize session to cleanup cache_keys to fix some errors

rhodecode/lib/rc_cache/cache_key_meta.py

@@ -40,7 +40,8 b' def free_cache_keys(*args):'
         try:
             for cache_proc in cache_keys_by_pid:
                 like_expression = '{}%'.format(cache_proc)
-                CacheKey.query().filter(CacheKey.cache_key.like(like_expression)).delete()
+                CacheKey.query().filter(
+                    CacheKey.cache_key.like(like_expression)).delete(synchronize_session='fetch')
                 cache_keys_by_pid.remove(cache_proc)
             Session().commit()
         except Exception: