Make the users empty when there is no passowrd file.
Make the users empty when there is no passowrd file.

Without this a default checkout that doesn't touch the trymaster
fails presubmit checks.


BUG=None
TEST=local

Review URL: https://chromiumcodereview.appspot.com/10796027

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@147431 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build