Update from 2.6.0rc6 to 2.6.0rc7.
UPGRADE URGENCY: HIGH
* [BUGFIX] Theoretical bug in ziplist fixed.
* [BUGFIX] Better out of memory handling (Log produced in log file).
* [BUGFIX] Incrementally flush RDB file on slave side while performing the
first synchronization with the master. This makes Redis less
blocking in environments where disk I/O is slow.
* [BUGFIX] Don't crash with Lua's redis.call() without arguments.
* [BUGFIX] Don't crash after a big number of Lua calls on 32 bit systems
because of a failed assertion.
* [BUGFIX] Fix SORT behaviour when called from scripting.
* [BUGFIX] Adjust slave PING period accordingly to REDIS_HZ define.
* [BUGFIX] BITCOUNT: fix crash on overflowing arguments.
* [BUGFIX] Return an error when SELECT argument is not an integer.
* [BUGFIX] Blocking operations on lists were completely reimplemented for
correctness. Now blocking list ops and pushes originated from
Lua scripts will play well together and will be replicated
and transmitted to the AOF correctly.
* [IMPROVED] Send async PING before starting replication to avoid blocking if
master allows us to connect but it is actually not able to reply.
* [IMPROVED] Support slave-priority for Redis Sentinel.
* [IMPROVED] Hiredis library updated.