nsqd: fix flakey TestHTTPEmptyChannelPOST
nsqd: fix flakey TestHTTPEmptyChannelPOST

MadBomber/nsq,sparklxb/nsq,ploxiln/nsq,nsqio/nsq,mreiferson/nsq,absolute8511/nsq,absolute8511/nsq,jehiah/nsq,rpau/nsq,szqh97/nsq,rpau/nsq,mreiferson/nsq,bitly/nsq,rpau/nsq,jlr52/nsq,szqh97/nsq,bitly/nsq,coderhaoxin/nsq,jlr52/nsq,mreiferson/nsq,ploxiln/nsq,MadBomber/nsq,absolute8511/nsq,MadBomber/nsq,nsqio/nsq,jehiah/nsq,jlr52/nsq,sparklxb/nsq,absolute8511/nsq,coderhaoxin/nsq,bitly/nsq,sparklxb/nsq,ploxiln/nsq,mreiferson/nsq,coderhaoxin/nsq,szqh97/nsq,sparklxb/nsq,sparklxb/nsq,MadBomber/nsq,ploxiln/nsq,jlr52/nsq,MadBomber/nsq,absolute8511/nsq,nsqio/nsq,coderhaoxin/nsq,rpau/nsq,szqh97/nsq,szqh97/nsq,jehiah/nsq,jehiah/nsq,coderhaoxin/nsq,jlr52/nsq,bitly/nsq,rpau/nsq,mreiferson/nsq,nsqio/nsq,ploxiln/nsq,nsqio/nsq,bitly/nsq,jehiah/nsq