Entered working directory before switch user.
Entered working directory before switch user.

If `chdir` into the working directory after switch user, the user may
fail because of permissions problem.

Review: https://reviews.apache.org/r/51782/

craimbert/mesos,Gilbert88/mesos,neilconway/mesos,craimbert/mesos,yuquanshan/customizedMesos,kaysoky/mesos,abudnik/mesos,reneploetz/mesos,gsantovena/mesos,kaysoky/mesos,chhsia0/mesos,dforsyth/mesos,Gilbert88/mesos,neilconway/mesos,jpeach/mesos,dforsyth/mesos,asamerh4/mesos,gsantovena/mesos,chhsia0/mesos,craimbert/mesos,Gilbert88/mesos,gsantovena/mesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,jpeach/mesos,dforsyth/mesos,zmalik/mesos,abudnik/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,asamerh4/mesos,kaysoky/mesos,chhsia0/mesos,kaysoky/mesos,dforsyth/mesos,asamerh4/mesos,zmalik/mesos,jpeach/mesos,jpeach/mesos,Aman-Jain-14/customizedMesos,verizonlabs/mesos,Gilbert88/mesos,andschwa/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,abudnik/mesos,Gilbert88/mesos,Aman-Jain-14/customizedMesos,gsantovena/mesos,kaysoky/mesos,zmalik/mesos,zmalik/mesos,andschwa/mesos,verizonlabs/mesos,craimbert/mesos,craimbert/mesos,kaysoky/mesos,abudnik/mesos,yuquanshan/customizedMesos,jpeach/mesos,asamerh4/mesos,reneploetz/mesos,reneploetz/mesos,gsantovena/mesos,Gilbert88/mesos,kaysoky/mesos,abudnik/mesos,yuquanshan/customizedMesos,neilconway/mesos,reneploetz/mesos,verizonlabs/mesos,neilconway/mesos,reneploetz/mesos,Gilbert88/mesos,verizonlabs/mesos,asamerh4/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,zmalik/mesos,jpeach/mesos,andschwa/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,andschwa/mesos,chhsia0/mesos,yuquanshan/customizedMesos,craimbert/mesos,abudnik/mesos,reneploetz/mesos,chhsia0/mesos,zmalik/mesos,craimbert/mesos,neilconway/mesos,verizonlabs/mesos,verizonlabs/mesos,chhsia0/mesos,zmalik/mesos,gsantovena/mesos,yuquanshan/customizedMesos,reneploetz/mesos,chhsia0/mesos,neilconway/mesos,abudnik/mesos,jpeach/mesos,andschwa/mesos,andschwa/mesos,gsantovena/mesos,dforsyth/mesos,asamerh4/mesos