[autotest] make test_that re-execute its board-sysroot-installed version

In the chroot path we will be adding a script which just sudo executes
test_that from the autotest source tree. However, we want to be running
test_that from within the autotest tree installed on the sysroot for
the board being tested. When test_that is run from elsewhere, it should
re-execute the board-installed version.

Down the road, there will be a few bootstrapping steps added before
re-executing the sysroot version. Specifically, board-autodetection, will
take place first, followed by any necessary emerge/quickmerge operations,
followed by re-executing the sysroot version of the script.

BUG=chromium:236471
TEST=(in chroot):
1) `test_that --board=frumpy asdf asdf`
ERROR:root:/build/frumpy/ does not exist. Have you run setup_board?
2) after setup_board for lumpy, but before build packages `test_that
--board=lumpy asdf asdf`
ERROR:root:/build/lumpy/usr/local/autotest/ does not exist. Have you run
build_packages?
3) after running build_packages `test_that --board=lumpy asdf asdf`
This script does not do anything yet.
Reached end of execution for script
/build/lumpy/usr/local/autotest/site_utils/test_that.py with args
['--board', 'lumpy', 'asdf', 'asdf'].

Change-Id: I0624984ee8d6a1b6fa0221a64d0e5ef96fd438c3
Reviewed-on: https://gerrit.chromium.org/gerrit/49384
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
1 file changed