Redis lru eviction: ERR wrong number of arguments for 'zrem' command

[domsj]

# journalctl -u alba-maintenance_nvmebackend-gmZSRdsVWG9NiQnT.service | grep random | tail -n 10
Mar 30 07:38:54 ovs05 alba[1233]: 2017-03-30 07:38:54 478736 +0200 - ovs05 - 1233/0 - alba/maintenance - 1833 - info - redis based lru eviction failed, doing fallback to random: Albamgr_protocol.Protocol.Error.Albamgr_exn(5, "Albamgr_protocol.Protocol.Error.Namespace_does_not_exist"); backtrace:; Raised at file "map.ml", line 122, characters 16-25; Called from file "src/core/lwt.ml", line 161, characters 4-40
Mar 30 07:38:54 ovs05 alba[1233]: 2017-03-30 07:38:54 478773 +0200 - ovs05 - 1233/0 - alba/maintenance - 1834 - info - Alba_eviction: starting random eviction
Mar 30 08:03:02 ovs05 alba[37280]: 2017-03-30 08:03:02 978731 +0200 - ovs05 - 37280/0 - alba/maintenance - 626 - info - redis based lru eviction failed, doing fallback to random: Redis.Client.Make(IO).Error("ERR wrong number of arguments for 'zrem' command"); backtrace:; Raised at file "map.ml", line 122, characters 16-25; Called from file "src/core/lwt.ml", line 161, characters 4-40
Mar 30 08:03:02 ovs05 alba[37280]: 2017-03-30 08:03:02 978755 +0200 - ovs05 - 37280/0 - alba/maintenance - 627 - info - Alba_eviction: starting random eviction
Mar 30 08:59:12 ovs05 alba[37280]: 2017-03-30 08:59:12 262407 +0200 - ovs05 - 37280/0 - alba/maintenance - 2278 - info - redis based lru eviction failed, doing fallback to random: Albamgr_protocol.Protocol.Error.Albamgr_exn(5, "Albamgr_protocol.Protocol.Error.Namespace_does_not_exist"); backtrace:; Raised at file "map.ml", line 122, characters 16-25; Called from file "src/core/lwt.ml", line 161, characters 4-40
Mar 30 08:59:12 ovs05 alba[37280]: 2017-03-30 08:59:12 262425 +0200 - ovs05 - 37280/0 - alba/maintenance - 2279 - info - Alba_eviction: starting random eviction
Mar 30 09:25:42 ovs05 alba[32348]: 2017-03-30 09:25:42 273708 +0200 - ovs05 - 32348/0 - alba/maintenance - 1213 - info - redis based lru eviction failed, doing fallback to random: Redis.Client.Make(IO).Error("ERR wrong number of arguments for 'zrem' command"); backtrace:; Raised at file "map.ml", line 122, characters 16-25; Called from file "src/core/lwt.ml", line 161, characters 4-40
Mar 30 09:25:42 ovs05 alba[32348]: 2017-03-30 09:25:42 273734 +0200 - ovs05 - 32348/0 - alba/maintenance - 1214 - info - Alba_eviction: starting random eviction
Mar 30 09:41:43 ovs05 alba[32348]: 2017-03-30 09:41:43 927197 +0200 - ovs05 - 32348/0 - alba/maintenance - 1649 - info - redis based lru eviction failed, doing fallback to random: Redis.Client.Make(IO).Error("ERR wrong number of arguments for 'zrem' command"); backtrace:; Raised at file "map.ml", line 122, characters 16-25; Called from file "src/core/lwt.ml", line 161, characters 4-40
Mar 30 09:41:43 ovs05 alba[32348]: 2017-03-30 09:41:43 927227 +0200 - ovs05 - 32348/0 - alba/maintenance - 1650 - info - Alba_eviction: starting random eviction

We don't see this every minute, so I guess most of the time it actually works as desired.
Maybe this error only occurs if we''re trying to remove 0 items from the zset? To be further investigated...