the failure signature is:

Unhandled IOError: [Errno 2] No such file or directory: 'touchpad-tests.py'

from https://stainless.corp.google.com/search?view=list&first_date=2018-03-06&last_date=2018-04-02&test=platform_GesturesRegressionTest&status=GOOD&status=FAIL&status=ERROR&exclude_cts=true&exclude_not_run=false&exclude_non_release=true&exclude_au=true&exclude_acts=true&exclude_retried=true&exclude_non_production=true

it looks like there was a system image fix between R67-10495.0.0 and R67-10496.0.0 (as R67 runs switch to "GOOD" at that point).  A quick look at the commit messages

https://crosland.corp.google.com/log/10495.0.0..10496.0.0

didn't have anything that screamed it is related.  Maybe something in the chromiumos-overlay changes should be backported to M66 and M65, though?