os: fix comment per CL 5370091
os: fix comment per CL 5370091

Made the edit in the wrong client before submitting.

TBR=r
CC=golang-dev
http://codereview.appspot.com/5374091
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go