redis-cli: Re-attach selected DB after auth
redis-cli: Re-attach selected DB after auth

Previously, if you did SELECT then AUTH, redis-cli
would show your SELECT'd db even though it didn't
happen.

Note: running into this situation is a (hopefully) very limited
used case of people using multiple DBs and AUTH all at the same
time.

Fixes antirez#1639

kts12345/redis,hanmichael/redis,laurencee/redis,erwin00776/redis-2.8-optimize,jaambee/redis,miminus/redis,LittlePeng/redis,jacklee0810/redis,nandhanurrevanth/redis,kolonse/redis,Jonavin/redis,alpha8/redis,upsoft/redis,alpha8/redis,jqk6/redis,adamweixuan/redis,quangnguyen90/redis,sidsen/redis,sidsen/redis,kts12345/redis,damy/redis,enginekit/redis,alpha8/redis,kts12345/redis,enginekit/redis,sidsen/redis,ideaar/redis,hanmichael/redis,erwin00776/redis-2.8-optimize,shanegxxiao/redis,laurencee/redis,kolonse/redis,Jonavin/redis,nandhanurrevanth/redis,enginekit/redis,liqiang199105/redis,upsoft/redis,shanegxxiao/redis,sidsen/redis,damy/redis,damy/redis,Cybermaxs/redis,jacklee0810/redis,liqiang199105/redis,LittlePeng/redis,adamweixuan/redis,StartTheShift/redis-shift,jacklee0810/redis,janeasystems/redis,ScottKaiGu/redis,Jonavin/redis,kolonse/redis,miminus/redis,fanxu/redis,Jonavin/redis,erwin00776/redis-2.8-optimize,nandhanurrevanth/redis,shanegxxiao/redis,adamweixuan/redis,liqiang199105/redis,ideaar/redis,kolonse/redis,quangnguyen90/redis,ideaar/redis,jacklee0810/redis,laurencee/redis,ideaar/redis,StartTheShift/redis-shift,damy/redis,ScottKaiGu/redis,ScottKaiGu/redis,enginekit/redis,jacklee0810/redis,shanegxxiao/redis,enginekit/redis,Jonavin/redis,miminus/redis,jqk6/redis,alpha8/redis,fanxu/redis,quangnguyen90/redis,liqiang199105/redis,alpha8/redis,liqiang199105/redis,quangnguyen90/redis,ScottKaiGu/redis,jaambee/redis,jaambee/redis,shanegxxiao/redis,kts12345/redis,hanmichael/redis,Cybermaxs/redis,adamweixuan/redis,jaambee/redis,miminus/redis,kolonse/redis,StartTheShift/redis-shift,ScottKaiGu/redis,janeasystems/redis,kts12345/redis,hanmichael/redis,adamweixuan/redis,upsoft/redis,jqk6/redis,janeasystems/redis,fanxu/redis,nandhanurrevanth/redis,jqk6/redis,nandhanurrevanth/redis,LittlePeng/redis,Cybermaxs/redis,miminus/redis,hanmichael/redis,laurencee/redis,ideaar/redis,Cybermaxs/redis,laurencee/redis,quangnguyen90/redis,jqk6/redis,janeasystems/redis,damy/redis,janeasystems/redis,sidsen/redis,fanxu/redis,sidsen/redis,Cybermaxs/redis,upsoft/redis,jaambee/redis,erwin00776/redis-2.8-optimize,upsoft/redis