fix grpcio_tools build on kokoro
fix grpcio_tools build on kokoro

deepaklukose/grpc,muxi/grpc,daniel-j-born/grpc,carl-mastrangelo/grpc,vjpai/grpc,yongni/grpc,carl-mastrangelo/grpc,muxi/grpc,pszemus/grpc,ncteisen/grpc,jtattermusch/grpc,mehrdada/grpc,firebase/grpc,nicolasnoble/grpc,quizlet/grpc,dgquintas/grpc,sreecha/grpc,deepaklukose/grpc,daniel-j-born/grpc,sreecha/grpc,Vizerai/grpc,stanley-cheung/grpc,Crevil/grpc,muxi/grpc,jboeuf/grpc,kumaralokgithub/grpc,fuchsia-mirror/third_party-grpc,kpayson64/grpc,ncteisen/grpc,vjpai/grpc,dgquintas/grpc,Crevil/grpc,PeterFaiman/ruby-grpc-minimal,muxi/grpc,chrisdunelm/grpc,vjpai/grpc,daniel-j-born/grpc,stanley-cheung/grpc,simonkuang/grpc,fuchsia-mirror/third_party-grpc,quizlet/grpc,donnadionne/grpc,murgatroid99/grpc,stanley-cheung/grpc,murgatroid99/grpc,PeterFaiman/ruby-grpc-minimal,firebase/grpc,chrisdunelm/grpc,carl-mastrangelo/grpc,firebase/grpc,daniel-j-born/grpc,murgatroid99/grpc,yongni/grpc,jtattermusch/grpc,fuchsia-mirror/third_party-grpc,pszemus/grpc,PeterFaiman/ruby-grpc-minimal,jboeuf/grpc,stanley-cheung/grpc,geffzhang/grpc,nicolasnoble/grpc,kskalski/grpc,Vizerai/grpc,muxi/grpc,mehrdada/grpc,grpc/grpc,kpayson64/grpc,PeterFaiman/ruby-grpc-minimal,jtattermusch/grpc,fuchsia-mirror/third_party-grpc,pszemus/grpc,geffzhang/grpc,grpc/grpc,vjpai/grpc,Crevil/grpc,ncteisen/grpc,Crevil/grpc,kumaralokgithub/grpc,Vizerai/grpc,nicolasnoble/grpc,fuchsia-mirror/third_party-grpc,simonkuang/grpc,muxi/grpc,jtattermusch/grpc,geffzhang/grpc,jtattermusch/grpc,kpayson64/grpc,thinkerou/grpc,ctiller/grpc,carl-mastrangelo/grpc,nicolasnoble/grpc,carl-mastrangelo/grpc,kpayson64/grpc,fuchsia-mirror/third_party-grpc,yongni/grpc,nicolasnoble/grpc,deepaklukose/grpc,grpc/grpc,grpc/grpc,stanley-cheung/grpc,donnadionne/grpc,thinkerou/grpc,murgatroid99/grpc,mehrdada/grpc,kskalski/grpc,chrisdunelm/grpc,kpayson64/grpc,pszemus/grpc,PeterFaiman/ruby-grpc-minimal,murgatroid99/grpc,kskalski/grpc,daniel-j-born/grpc,deepaklukose/grpc,quizlet/grpc,donnadionne/grpc,Crevil/grpc,mehrdada/grpc,geffzhang/grpc,jtattermusch/grpc,geffzhang/grpc,yongni/grpc,mehrdada/grpc,kumaralokgithub/grpc,simonkuang/grpc,chrisdunelm/grpc,ctiller/grpc,geffzhang/grpc,simonkuang/grpc,matt-kwong/grpc,grpc/grpc,sreecha/grpc,kumaralokgithub/grpc,ncteisen/grpc,PeterFaiman/ruby-grpc-minimal,ejona86/grpc,murgatroid99/grpc,nicolasnoble/grpc,stanley-cheung/grpc,stanley-cheung/grpc,ejona86/grpc,kpayson64/grpc,simonkuang/grpc,thinkerou/grpc,firebase/grpc,carl-mastrangelo/grpc,chrisdunelm/grpc,ncteisen/grpc,dgquintas/grpc,Vizerai/grpc,adelez/grpc,muxi/grpc,chrisdunelm/grpc,quizlet/grpc,grpc/grpc,adelez/grpc,jtattermusch/grpc,thinkerou/grpc,quizlet/grpc,ctiller/grpc,pszemus/grpc,nicolasnoble/grpc,daniel-j-born/grpc,dgquintas/grpc,mehrdada/grpc,mehrdada/grpc,yongni/grpc,ctiller/grpc,muxi/grpc,ctiller/grpc,nicolasnoble/grpc,vjpai/grpc,dgquintas/grpc,chrisdunelm/grpc,carl-mastrangelo/grpc,donnadionne/grpc,pszemus/grpc,ctiller/grpc,ncteisen/grpc,matt-kwong/grpc,nicolasnoble/grpc,jboeuf/grpc,simonkuang/grpc,vjpai/grpc,vjpai/grpc,mehrdada/grpc,ncteisen/grpc,ejona86/grpc,Vizerai/grpc,carl-mastrangelo/grpc,pszemus/grpc,ejona86/grpc,matt-kwong/grpc,sreecha/grpc,matt-kwong/grpc,firebase/grpc,kpayson64/grpc,ejona86/grpc,carl-mastrangelo/grpc,adelez/grpc,adelez/grpc,thinkerou/grpc,Crevil/grpc,nicolasnoble/grpc,geffzhang/grpc,muxi/grpc,PeterFaiman/ruby-grpc-minimal,ctiller/grpc,jtattermusch/grpc,carl-mastrangelo/grpc,kumaralokgithub/grpc,adelez/grpc,vjpai/grpc,ejona86/grpc,Vizerai/grpc,kpayson64/grpc,firebase/grpc,kskalski/grpc,grpc/grpc,kumaralokgithub/grpc,jtattermusch/grpc,grpc/grpc,kskalski/grpc,carl-mastrangelo/grpc,pszemus/grpc,dgquintas/grpc,PeterFaiman/ruby-grpc-minimal,chrisdunelm/grpc,kumaralokgithub/grpc,donnadionne/grpc,donnadionne/grpc,donnadionne/grpc,chrisdunelm/grpc,yongni/grpc,sreecha/grpc,mehrdada/grpc,firebase/grpc,thinkerou/grpc,firebase/grpc,ejona86/grpc,fuchsia-mirror/third_party-grpc,dgquintas/grpc,thinkerou/grpc,thinkerou/grpc,kskalski/grpc,pszemus/grpc,ctiller/grpc,ctiller/grpc,matt-kwong/grpc,jboeuf/grpc,thinkerou/grpc,donnadionne/grpc,ejona86/grpc,daniel-j-born/grpc,dgquintas/grpc,kumaralokgithub/grpc,Vizerai/grpc,adelez/grpc,jboeuf/grpc,sreecha/grpc,Crevil/grpc,stanley-cheung/grpc,ncteisen/grpc,nicolasnoble/grpc,ncteisen/grpc,yongni/grpc,donnadionne/grpc,deepaklukose/grpc,pszemus/grpc,jtattermusch/grpc,mehrdada/grpc,chrisdunelm/grpc,stanley-cheung/grpc,dgquintas/grpc,quizlet/grpc,muxi/grpc,mehrdada/grpc,matt-kwong/grpc,simonkuang/grpc,grpc/grpc,stanley-cheung/grpc,grpc/grpc,kumaralokgithub/grpc,dgquintas/grpc,deepaklukose/grpc,firebase/grpc,quizlet/grpc,kskalski/grpc,jtattermusch/grpc,murgatroid99/grpc,ejona86/grpc,adelez/grpc,murgatroid99/grpc,jboeuf/grpc,ncteisen/grpc,mehrdada/grpc,grpc/grpc,sreecha/grpc,nicolasnoble/grpc,ncteisen/grpc,jboeuf/grpc,deepaklukose/grpc,daniel-j-born/grpc,ejona86/grpc,vjpai/grpc,donnadionne/grpc,stanley-cheung/grpc,thinkerou/grpc,murgatroid99/grpc,sreecha/grpc,Vizerai/grpc,grpc/grpc,vjpai/grpc,fuchsia-mirror/third_party-grpc,donnadionne/grpc,pszemus/grpc,firebase/grpc,Crevil/grpc,jboeuf/grpc,sreecha/grpc,thinkerou/grpc,Vizerai/grpc,sreecha/grpc,pszemus/grpc,simonkuang/grpc,muxi/grpc,ctiller/grpc,ejona86/grpc,kskalski/grpc,kpayson64/grpc,daniel-j-born/grpc,adelez/grpc,ctiller/grpc,stanley-cheung/grpc,jboeuf/grpc,firebase/grpc,quizlet/grpc,Vizerai/grpc,jboeuf/grpc,sreecha/grpc,jtattermusch/grpc,kpayson64/grpc,matt-kwong/grpc,quizlet/grpc,jboeuf/grpc,ncteisen/grpc,dgquintas/grpc,geffzhang/grpc,chrisdunelm/grpc,yongni/grpc,yongni/grpc,thinkerou/grpc,ejona86/grpc,deepaklukose/grpc,fuchsia-mirror/third_party-grpc,PeterFaiman/ruby-grpc-minimal,adelez/grpc,fuchsia-mirror/third_party-grpc,muxi/grpc,murgatroid99/grpc,donnadionne/grpc,matt-kwong/grpc,PeterFaiman/ruby-grpc-minimal,geffzhang/grpc,vjpai/grpc,kskalski/grpc,Vizerai/grpc,vjpai/grpc,Crevil/grpc,ctiller/grpc,simonkuang/grpc,jboeuf/grpc,deepaklukose/grpc,matt-kwong/grpc,kpayson64/grpc,carl-mastrangelo/grpc,firebase/grpc,sreecha/grpc