brillo package: Do not require chroot for --create-source.

It's not needed and induces substantial overhead on first-time runs.

BUG=brillo:883
TEST=Ran brillo package --create-source, ebuild created, no chroot used.
TEST=Unit tests.

Change-Id: Iebba73c1ec474d01c9849ab80d36b3eade107da5
Reviewed-on: https://chromium-review.googlesource.com/266951
Trybot-Ready: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
1 file changed