gs_archive_server: fix nebraska import issue

Nebraska.py is added to PYTHONPATH, so gs_archive_server should be able
to import nebraska.py directly. But if gs_archive_server is triggered
from ~/chromiumos/src/platform/dev, it will import nebraska, the python
package,instead of nebraska.py, thus throwing an AttributeError when the
module is eventually used. To mitigate this, catch the exception and
import nebraska.py from the nebraska package directly.

BUG=chromium:1078188
TEST=Manually tested. Details can be found at
http://gpaste/5025076468514816

Change-Id: I9c0fc1f9cb08e180d67f17d60577a33adbc404ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2296249
Tested-by: Sanika Kulkarni <sanikak@chromium.org>
Auto-Submit: Sanika Kulkarni <sanikak@chromium.org>
Reviewed-by: Congbin Guo <guocb@chromium.org>
Commit-Queue: Sanika Kulkarni <sanikak@chromium.org>
1 file changed