Preserve compress method when re-sign Android image

TEST=sign_android_image.sh rootfs /path/to/tests/devkeys/android
     # unsquash -s still shows gzip (previous script always use lzo)
BUG=chromium:705247
BRANCH=none

Change-Id: If95686d293123a069ce36bc53cbea3a08aa3e7ab
Reviewed-on: https://chromium-review.googlesource.com/461205
Commit-Ready: Victor Hsieh <victorhsieh@chromium.org>
Tested-by: Victor Hsieh <victorhsieh@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed