upgrade omnibus redis to latest release
it seems that omnibus redis is version 2.8.0 which has serious bugs inside, including ones that are causing database corruptions like in #395 (closed).
Current maintenance version of redis is 2.8.20 and it seems that such problems as the one listed are solved in 2.8.6
Also redis 3.x is stable but I don't know if this would introduce new bugs, anyway there is no reason for not upgrading redis to 2.8.20 ASAP.