Updated implemenation of os::isfile to match Python (contributed by Ben Mahler, https://reviews.apache.org/r/7174).
Updated implemenation of os::isfile to match Python (contributed by
Ben Mahler, https://reviews.apache.org/r/7174).

git-svn-id: 03d7800a49d8905ef4fbcc296184319e19243493@1396422 13f79535-47bb-0310-9956-ffa450edef68

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