This is basically b/70539494 (and  crbug.com/800657  if it gets worse)

+Ilja, the lock failure looks getting more common

https://stainless.corp.google.com/search?view=list&first_date=2018-01-18&last_date=2018-01-31&test=cheets_%5BCG%5DTS&status=FAIL&status=ERROR&reason=lock&exclude_cts=false&exclude_not_run=false&exclude_non_release=false&exclude_au=true&exclude_acts=true&exclude_retried=true&exclude_non_production=true

or rather merging to a single bug so that the discussion won't diverge too much