Cancel SHUTDOWN if initial AOF is being written
Cancel SHUTDOWN if initial AOF is being written

Fixes #1826 (and many other reports of the same problem)

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