queue: reproduce failure under race detector
queue: reproduce failure under race detector

Using multiple clients help reproducing the failure. Indeed, it's
broken.

ggarnier/tsuru,gwmoura/tsuru,guilhermebr/tsuru,mderaldo/tsuru,cezarsa/tsuru,firebitsbr/tsuru,hugoantunes/tsuru,ggarnier/tsuru,ArxdSilva/tsuru,ArxdSilva/tsuru,Endika/tsuru,4eek/tsuru,jblancett/tsuru,gciotta/tsuru,tuxmonteiro/tsuru,4eek/tsuru,kgrvamsi/tsuru,4eek/tsuru,gciotta/tsuru,firebitsbr/tsuru,tuxmonteiro/tsuru,gwmoura/tsuru,firebitsbr/tsuru,ggarnier/tsuru,tsuru/tsuru,ggarnier/tsuru,Endika/tsuru,gwmoura/tsuru,ArxdSilva/tsuru,kgrvamsi/tsuru,RichardKnop/tsuru,tsuru/tsuru,cgvarela/tsuru,RichardKnop/tsuru,cezarsa/tsuru,mderaldo/tsuru,gciotta/tsuru,hcxiong/tsuru,cgvarela/tsuru,guilhermebr/tsuru,hugoantunes/tsuru,cgvarela/tsuru,jblancett/tsuru,tsuru/tsuru,tsuru/tsuru,cezarsa/tsuru,Endika/tsuru,RichardKnop/tsuru,guilhermebr/tsuru,hcxiong/tsuru,mderaldo/tsuru,tuxmonteiro/tsuru,ArxdSilva/tsuru,cezarsa/tsuru,kgrvamsi/tsuru,jblancett/tsuru,hcxiong/tsuru,guilhermebr/tsuru