This removes some spurious noise from the build_image output.
BUG=None
TEST=`./build_image` still worked and is quieter
Change-Id: Ic5d89a462dc137a1a710f77dc16cee401e0083b2
Reviewed-on: https://gerrit.chromium.org/gerrit/35426
Reviewed-by: David James <davidjames@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>