Once one EWS bot fails, it adds the merging blocked keyword to the PR. Sadly, this keyword prevents other EWS bots from processing the PR which is a clear regression compared to the behavior of EWS on bugzilla.
*** This bug has been marked as a duplicate of bug 240169 ***
Some background: This was a design decision I made because I thought it's what cq- did. In fact, it's what r- does, and while merging-blocked sort of means r- in GitHub, it's a more obvious parallel to cq-. Couple this with the fact that engineers commonly use EWS to test known bad changes to see exactly where they are failing, stopping EWS when one EWS queue fails seems to be a bad idea.