Fix minor bug with nightly tests.

Check that iter_results is not empty before trying to check a
value in it.

BUG=None
TEST=None

Change-Id: I60946e4351c137c2ba79fc978d1f6ec6635cc40e
Reviewed-on: https://chrome-internal-review.googlesource.com/229755
Commit-Ready: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
Reviewed-by: Rahul Chaudhry <rahulchaudhry@google.com>
1 file changed