BITFIELD: refactoring & fix of retval on FAIL.
BITFIELD: refactoring & fix of retval on FAIL.

pedigree/redis,pedigree/redis,xuguruogu/redis,4396/redis,4396/redis,pedigree/redis,4396/redis,xuguruogu/redis,4396/redis,xuguruogu/redis,pedigree/redis,xuguruogu/redis