[moblab] Change the external mounting script to preserve permissions.
Some of the files on the external file need to keep the permissions
granted at creation time, reduce the scope of what is chowned to
moblab.
Fix issue where fsck sometimes failed because the usb had been mounted
by another part of chromeos.
BUG=chromium:752556,chromium:750921
TEST=local moblab testing
Change-Id: If03fb27fe744ecd9e694c5b7124655684958ca14
Reviewed-on: https://chromium-review.googlesource.com/602614
Commit-Ready: Keith Haddow <haddowk@chromium.org>
Tested-by: Keith Haddow <haddowk@chromium.org>
Reviewed-by: Keith Haddow <haddowk@chromium.org>
Reviewed-by: Michael Tang <ntang@chromium.org>
(cherry picked from commit 6c649639a56b8e78afcda5bf966a91fb27030979)
Reviewed-on: https://chromium-review.googlesource.com/602885
Commit-Queue: Keith Haddow <haddowk@chromium.org>
2 files changed
