Fix async issue in tests.
Fix async issue in tests.

tizzybec/tilemill,isaacs/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,makinacorpus/tilemill,paulovieira/tilemill-clima,Teino1978-Corp/Teino1978-Corp-tilemill,mbrukman/tilemill,nyimbi/tilemill,tilemill-project/tilemill,nyimbi/tilemill,paulovieira/tilemill-clima,Zhao-Qi/tilemill,florianf/tileoven,paulovieira/tilemill-clima,mbrukman/tilemill,mbrukman/tilemill,MappingKat/tilemill,nyimbi/tilemill,fxtentacle/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,Zhao-Qi/tilemill,fxtentacle/tilemill,MappingKat/tilemill,tizzybec/tilemill,fxtentacle/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,tizzybec/tilemill,Zhao-Qi/tilemill,MappingKat/tilemill,tilemill-project/tilemill,MappingKat/tilemill,isaacs/tilemill,Zhao-Qi/tilemill,florianf/tileoven,florianf/tileoven,Zhao-Qi/tilemill,nyimbi/tilemill,mbrukman/tilemill,fxtentacle/tilemill,isaacs/tilemill,fxtentacle/tilemill,tizzybec/tilemill,mbrukman/tilemill,paulovieira/tilemill-clima,nyimbi/tilemill,MappingKat/tilemill,tilemill-project/tilemill,tizzybec/tilemill,makinacorpus/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,paulovieira/tilemill-clima