In legacy/trac#29761, we discovered that 0.2.9 often fails, and when one allow failures run fails, the next fails too. I want to add a sleep between allow failures rounds to hopefully allow 0.2.9 to recover. Should we only add the sleep for 0.2.9? Probably, otherwise we won't notice regressions. We might also need to: * adjust the 0.2.9 bootstrap timings * remove 0.2.9 from CI