[GPU] bug fix
[GPU] bug fix

maaskola/GPy,beckdaniel/GPy,gusmaogabriels/GPy,ptonner/GPy,maaskola/GPy,TianpeiLuke/GPy,buntyke/GPy,esiivola/GPYgradients,gusmaogabriels/GPy,beckdaniel/GPy,befelix/GPy,befelix/GPy,ysekky/GPy,jameshensman/GPy,avehtari/GPy,strongh/GPy,AlexGrig/GPy,TianpeiLuke/GPy,TianpeiLuke/GPy,mikecroucher/GPy,ysekky/GPy,dhhjx880713/GPy,maaskola/GPy,befelix/GPy,PredictiveScienceLab/GPy,Dapid/GPy,strongh/GPy,fivejjs/GPy,Dapid/GPy,buntyke/GPy,SheffieldML/GPy,jameshensman/GPy,mikecroucher/GPy,buntyke/GPy,gusmaogabriels/GPy,fivejjs/GPy,mikecroucher/GPy,esiivola/GPYgradients,avehtari/GPy,jameshensman/GPy,SheffieldML/GPy,dhhjx880713/GPy,SheffieldML/GPy,dhhjx880713/GPy,dhhjx880713/GPy,buntyke/GPy,ptonner/GPy,ysekky/GPy,mikecroucher/GPy,ysekky/GPy,esiivola/GPYgradients,Dapid/GPy,avehtari/GPy,ptonner/GPy,ptonner/GPy,Dapid/GPy,fivejjs/GPy,beckdaniel/GPy,strongh/GPy,SheffieldML/GPy,AlexGrig/GPy,avehtari/GPy,PredictiveScienceLab/GPy,PredictiveScienceLab/GPy,jameshensman/GPy,beckdaniel/GPy,AlexGrig/GPy,befelix/GPy,PredictiveScienceLab/GPy,esiivola/GPYgradients,AlexGrig/GPy,maaskola/GPy