> Making the timeout bigger can be a possibility, certainly, but this also means the builder will get stuck more time in race conditions or deadlocks :(

Race conditions and deadlocks are less likely than false alarms of builds failed because the timeout is too short.

So far, I'm only aware of this specific buildbot worker which is too slow for "(timeout: 25 min, worker timeout: 30 min)". So just increase the timeout to 40 min, no?