Reids 3.0.0.RC4 常规改进：
* [FIX] redis-cli CSV output NIL spurious newline removed. (Matt Collier)
* [FIX] Memory efficiency test in unit test is now much faster: it affacted
the total "make test" execution time in a bad way. (Salvatore
* [FIX] Fixes and improvements to dict.c and LRU eviction. Redis 3.0.0 new
LRU eviction had bugs creating high latency spikes when LRU was
happening during the keys dictionary rehashing. This bug is not
present into 2.8, was 3.0 specific. As a side effect of this issue
dict.c is now improved, and LRU algorithm is more precise (better
approximates true LRU). This was a joint effort, see issue
#2306 for details. (Oran Agra, Sun He, Salvatore Sanfilippo).
Thanks to Charsyam for spotting an integer overflow.