devmode-test: switch from mount_helper to chromite.lib.image_lib

The local mount_helper API is built on the script
which can be a bit crufty/opaque when flakes/failures are hit.  Switch
to the pure Python chromite.lib.image_lib API which has better logging
and error triaging.  It also has better recovery when kernels flake.

This also has a nicer property of only having to mount the single
partition that we care about (stateful) rather than extraneous ones
we don't care about (rootfs).

TEST=` --verbose betty chromiumos_test_image.bin` still passes

Change-Id: I8a9fe29dd047fe0cc4e7a32a6f05fcbb8b326bbb
Reviewed-by: Achuith Bhandarkar <>
Tested-by: Mike Frysinger <>
Commit-Queue: Mike Frysinger <>
1 file changed